A viewer who connects before the stream's first segment is answered in H.264. If the stream turns out to be AV1 only, the session used to skip every segment's video while audio kept the player from noticing; now a segment whose first codec the viewer takes isn't the session's ends the session, and the viewer reconnects into it (also when a stream changes codec). The answer waits on the session too, which could otherwise end before ICE gathering completed and leave it waiting forever. - A browser that doesn't decode the AV1 source smoothly keeps AV1 when the stream has no H.264 fallback: a struggling decoder beats no video. - The native player tags its video view player-video once video frames arrive, and the AV1 Maestro flow waits on that: the loading overlay also clears on audio alone.