diff --git a/package-lock.json b/package-lock.json
index 7f8544c..98a2697 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -8,6 +8,7 @@
       "name": "frontend-helper",
       "version": "0.1.0",
       "dependencies": {
+        "hls.js": "1.7.3",
         "next": "15.5.28",
         "react": "19.0.0",
         "react-dom": "19.0.0"
@@ -4321,6 +4322,12 @@
         "node": ">= 0.4"
       }
     },
+    "node_modules/hls.js": {
+      "version": "1.7.3",
+      "resolved": "https://registry.npmjs.org/hls.js/-/hls.js-1.7.3.tgz",
+      "integrity": "sha512-MsPlx6yVW4Qv4C7mEVou4/gk/5cN2dVxOTnrNjPSmyH2f0Ln+/UkG10Ax1PE6OvrmTVPKgQYozTtBaPOuCzq7A==",
+      "license": "Apache-2.0"
+    },
     "node_modules/ignore": {
       "version": "5.3.2",
       "resolved": "https://registry.npmjs.org/ignore/-/ignore-5.3.2.tgz",
diff --git a/package.json b/package.json
index e37a838..e50b341 100644
--- a/package.json
+++ b/package.json
@@ -11,6 +11,7 @@
     "test": "vitest run"
   },
   "dependencies": {
+    "hls.js": "1.7.3",
     "next": "15.5.28",
     "react": "19.0.0",
     "react-dom": "19.0.0"
diff --git a/src/app/globals.css b/src/app/globals.css
index e143da7..f586a20 100644
--- a/src/app/globals.css
+++ b/src/app/globals.css
@@ -24,6 +24,8 @@ button:disabled { opacity: .5; cursor: not-allowed; }
 .post-who time { color: var(--grey); font-size: 13px; }
 .post-text { margin: 0; white-space: pre-wrap; overflow-wrap: anywhere; line-height: 1.5; }
 .post-media img { display: block; width: 100%; height: auto; border-radius: 8px; }
+.post-video { background: #000; border-radius: 8px; overflow: hidden; }
+.post-video video { display: block; width: 100%; max-height: 520px; background: #000; }
 .post-stats { display: flex; gap: 16px; color: var(--grey); font-size: 14px; }
 .heart { color: var(--red); }
 .feed-message { text-align: center; color: var(--grey); padding: 32px 16px; }
diff --git a/src/components/PostCard.tsx b/src/components/PostCard.tsx
index 8b9e0a7..f36d04a 100644
--- a/src/components/PostCard.tsx
+++ b/src/components/PostCard.tsx
@@ -1,3 +1,4 @@
+import { VideoPlayer } from "@/components/VideoPlayer";
 import { initials, relativeTime, type CardPost } from "@/lib/feed-model";
 
 export function PostCard({ post, now }: { post: CardPost; now?: number }) {
@@ -19,7 +20,11 @@ export function PostCard({ post, now }: { post: CardPost; now?: number }) {
       </header>
       {post.text ? <p className="post-text">{post.text}</p> : null}
       {post.media.map((m, i) =>
-        m.src ? (
+        m.kind === "video" && m.hlsUrl ? (
+          <div className="post-media post-video" key={i}>
+            <VideoPlayer hlsUrl={m.hlsUrl} poster={m.src} label={`Video from ${post.authorName}`} />
+          </div>
+        ) : m.src ? (
           <div className={m.kind === "video" ? "post-media post-video" : "post-media"} key={i}>
             {/* eslint-disable-next-line @next/next/no-img-element */}
             <img src={m.src} alt={m.kind === "video" ? "Video thumbnail" : ""} loading="lazy" />
diff --git a/src/components/VideoPlayer.tsx b/src/components/VideoPlayer.tsx
new file mode 100644
index 0000000..be96a78
--- /dev/null
+++ b/src/components/VideoPlayer.tsx
@@ -0,0 +1,69 @@
+"use client";
+
+import { useEffect, useRef, useState } from "react";
+import { choosePlayback, supportsNativeHls } from "@/lib/video-playback";
+
+export interface VideoPlayerProps {
+  hlsUrl: string;
+  poster: string | null;
+  label: string;
+}
+
+/**
+ * Real <video controls>. Native HLS where the browser has it, otherwise hls.js,
+ * loaded only when a video card mounts. Never autoplays.
+ */
+export function VideoPlayer({ hlsUrl, poster, label }: VideoPlayerProps) {
+  const ref = useRef<HTMLVideoElement>(null);
+  const [failed, setFailed] = useState(false);
+
+  useEffect(() => {
+    const video = ref.current;
+    if (!video) return;
+    let destroy: (() => void) | undefined;
+    let cancelled = false;
+    const native = supportsNativeHls(video);
+    if (native) {
+      if (choosePlayback(hlsUrl, { nativeHls: true, hlsJsSupported: false }) === "native") {
+        video.src = hlsUrl;
+      }
+      return;
+    }
+    import("hls.js")
+      .then(({ default: Hls }) => {
+        if (cancelled) return;
+        const mode = choosePlayback(hlsUrl, { nativeHls: false, hlsJsSupported: Hls.isSupported() });
+        if (mode !== "hlsjs") {
+          setFailed(true);
+          return;
+        }
+        const hls = new Hls();
+        hls.on(Hls.Events.ERROR, (_e, data) => {
+          if (data.fatal) setFailed(true);
+        });
+        hls.loadSource(hlsUrl);
+        hls.attachMedia(video);
+        destroy = () => hls.destroy();
+      })
+      .catch(() => setFailed(true));
+    return () => {
+      cancelled = true;
+      destroy?.();
+    };
+  }, [hlsUrl]);
+
+  if (failed && poster) {
+    // eslint-disable-next-line @next/next/no-img-element
+    return <img src={poster} alt="Video thumbnail" loading="lazy" />;
+  }
+  return (
+    <video
+      ref={ref}
+      controls
+      playsInline
+      preload="none"
+      poster={poster ?? undefined}
+      aria-label={label}
+    />
+  );
+}
diff --git a/src/lib/feed-model.ts b/src/lib/feed-model.ts
index b8520ea..d3363fa 100644
--- a/src/lib/feed-model.ts
+++ b/src/lib/feed-model.ts
@@ -5,6 +5,8 @@ export interface CardMedia {
   kind: "image" | "video";
   /** Image source (images) or poster (videos). May be null for a bare video. */
   src: string | null;
+  /** Mux HLS playlist (videos only). Null when the video is not ready yet. */
+  hlsUrl?: string | null;
 }
 
 export interface CardPost {
@@ -47,6 +49,18 @@ function authorName(author: Obj): string {
   return full || "Unknown";
 }
 
+/** The HLS URL only when it is https on stream.mux.com. */
+export function muxHlsUrl(v: unknown): string | null {
+  const s = str(v);
+  if (!s) return null;
+  try {
+    const u = new URL(s);
+    return u.protocol === "https:" && u.hostname === "stream.mux.com" ? s : null;
+  } catch {
+    return null;
+  }
+}
+
 function toMedia(raw: unknown): CardMedia[] {
   if (!Array.isArray(raw)) return [];
   const items = raw
@@ -56,7 +70,9 @@ function toMedia(raw: unknown): CardMedia[] {
   const out: CardMedia[] = [];
   for (const { m } of items) {
     if (m.mediaType === "video") {
-      out.push({ kind: "video", src: str(m.thumbnailUrl) });
+      const thumb = str(m.thumbnailUrl);
+      const hls = muxHlsUrl(m.hlsUrl);
+      if (thumb || hls) out.push({ kind: "video", src: thumb, hlsUrl: hls });
       continue;
     }
     const src = str(m.imageMediumWebpUrl) ?? str(m.imageMediumUrl) ?? str(m.imageUrl);
diff --git a/src/lib/video-playback.ts b/src/lib/video-playback.ts
new file mode 100644
index 0000000..6c0407b
--- /dev/null
+++ b/src/lib/video-playback.ts
@@ -0,0 +1,21 @@
+// Chooses how a feed video plays. Pure, so it is unit-testable without a browser.
+
+export type Playback = "none" | "native" | "hlsjs";
+
+export interface PlaybackEnv {
+  /** True when the browser can play .m3u8 directly (Safari). */
+  nativeHls: boolean;
+  /** True when hls.js (Media Source Extensions) is supported. */
+  hlsJsSupported: boolean;
+}
+
+/** No hlsUrl: thumbnail only. Native HLS wins; hls.js is the fallback. */
+export function choosePlayback(hlsUrl: string | null | undefined, env: PlaybackEnv): Playback {
+  if (!hlsUrl) return "none";
+  if (env.nativeHls) return "native";
+  return env.hlsJsSupported ? "hlsjs" : "none";
+}
+
+export function supportsNativeHls(video: Pick<HTMLVideoElement, "canPlayType">): boolean {
+  return video.canPlayType("application/vnd.apple.mpegurl") !== "";
+}
diff --git a/tests/video-playback.test.ts b/tests/video-playback.test.ts
new file mode 100644
index 0000000..b083e1f
--- /dev/null
+++ b/tests/video-playback.test.ts
@@ -0,0 +1,55 @@
+import { describe, expect, it } from "vitest";
+import { createElement } from "react";
+import { renderToStaticMarkup } from "react-dom/server";
+import { PostCard } from "@/components/PostCard";
+import { toCardPosts } from "@/lib/feed-model";
+import { choosePlayback, supportsNativeHls } from "@/lib/video-playback";
+
+const HLS = "https://stream.mux.com/abc.m3u8";
+const item = (media: Record<string, unknown>) => ({
+  type: "post",
+  publishedAt: "2026-10-19T10:00:00Z",
+  post: { id: "1", content: "hi", author: { displayName: "Ann" }, mediaItems: [media] },
+});
+const html = (media: Record<string, unknown>) =>
+  renderToStaticMarkup(createElement(PostCard, { post: toCardPosts([item(media)])[0] }));
+
+describe("choosePlayback", () => {
+  it("no hlsUrl means no player", () => {
+    expect(choosePlayback(null, { nativeHls: true, hlsJsSupported: true })).toBe("none");
+    expect(choosePlayback(undefined, { nativeHls: false, hlsJsSupported: true })).toBe("none");
+  });
+  it("uses native HLS where supported, hls.js otherwise", () => {
+    expect(choosePlayback(HLS, { nativeHls: true, hlsJsSupported: true })).toBe("native");
+    expect(choosePlayback(HLS, { nativeHls: false, hlsJsSupported: true })).toBe("hlsjs");
+  });
+  it("falls back to none when neither is available", () => {
+    expect(choosePlayback(HLS, { nativeHls: false, hlsJsSupported: false })).toBe("none");
+  });
+  it("detects native HLS from canPlayType", () => {
+    expect(supportsNativeHls({ canPlayType: () => "maybe" })).toBe(true);
+    expect(supportsNativeHls({ canPlayType: () => "" })).toBe(false);
+  });
+});
+
+describe("video media in the card", () => {
+  const video = { mediaType: "video", thumbnailUrl: "https://i/v.jpg" };
+  it("hlsUrl present renders an accessible controls player with the poster", () => {
+    const out = html({ ...video, hlsUrl: HLS });
+    expect(out).toContain("<video");
+    expect(out).toContain("controls");
+    expect(out).toContain('poster="https://i/v.jpg"');
+    expect(out).toContain('aria-label="Video from Ann"');
+    expect(out).not.toContain("autoplay");
+  });
+  it("hlsUrl absent shows the thumbnail only, no player", () => {
+    const out = html(video);
+    expect(out).not.toContain("<video");
+    expect(out).toContain('src="https://i/v.jpg"');
+  });
+  it("rejects an hlsUrl not on stream.mux.com", () => {
+    const out = html({ ...video, hlsUrl: "https://evil.example/x.m3u8" });
+    expect(out).not.toContain("<video");
+    expect(out).toContain('src="https://i/v.jpg"');
+  });
+});