Currently the synchronization takes into account the server time but not the time taken during the request.

Implement a button that triggers an eagle sound to the entire room

Example sound: https://www.youtube.com/watch?v=IdFxnbZtu1I

Add a way to easily create different environments per team. Maybe add Slack Button support to make it easy to do so.

Add a persistence layer to allow the playlist to survive deploys and allow horizontal scalling (for example using amazon elastic beanstalk autoscalling)

The Youtube Data API has that info but I'm not sure its accessible to people who aren't the uploader.

Change the vote to skip button to trigger a timed room vote to skip the song.

Remember username between sessions and synchronize usernames on the same browser

Keep a list of previously played videos so people can easily see what played in the past.

Implement a mobile ready layout

Add the user name of the user who submitted the video to the external viewer.

Automatically add related youtube videos when the playlist becomes empty

Implement a bot command like @bot what's playing that replies with the currently playing video

Use the javascript fullscreen API to implement a Fullscreen mode

Make the bot announce to the room it's in which song is currently playing. Maybe also add a way to ask it directly.

Use some sort of dynamic configuration instead of rc to allow configuration changes without rebooting the server

Implement a way for people to switch rooms.

Add a direct link to the videos on the playlist interface