As of build 772, there is a new issue observed with the vrc stream sync video players. While adding a track works, once a video is started, any state change to the video after is reflected locally on the owner of the video player and no one else.
Reproduction Steps:
  1. Go to wrld_fff5d510-fc53-4e88-9d4e-1e0e45a17aff
  2. Select the stream sync video player (option 1)
  3. Play any video, eg https://www.youtube.com/watch?v=yDjbTjelkgk
  4. Video will start playing for you and anyone else in the map
  5. Hit ANY controls that send an RPC call to the stream sync player, (pause, stop, fast forward, rewind, live/normal mode)
  6. Observe that the video will only pause/stop/fastfoward etc on the video owners client, and not on anyone elses. The same also applies when a stopped video is restarted.
If video controls are released to everyone, only the person who enters a url (who becomes the video owner) can see any state change to the video after it starts. If someone other than the video owner hits the controls, the state change is observed on the video owners client only.
This bug seems to affect all maps that use the sync stream component (eg, jetdogs stream player example map).
the video sync component seems to be unaffected and works as expected
In the vrchat logs, stream sync rpc calls look like they are being deffered because the instigator is not local.
If a stream sync player has a predefined play list, only the video owner can change tracks and see them as well