Start video muted

This lets us get auto play in firefox

web/src/pages/watch/[user].tsx

@@ -43,7 +43,7 @@ const Video = ({user}: {user: string}) => {
     }
   }, [videoRef, user])
 
-  return <video ref={videoRef} autoPlay controls playsInline />
+  return <video ref={videoRef} autoPlay muted controls playsInline />
 }
 
 export default () => {