I like your idea. Did you know there is already a custom music option in Roll20? It is called Soundcloud, and is accessible through a little music-note button at the top of the GM's chat room. The service used for this is Soundcloud not YouTube so if you want to upload your own sounds, go to <a href="http://www.soundcloud.com" rel="nofollow">http://www.soundcloud.com</a> For another approach, I have also heard that you can use Google Hangouts to start all the players on the same YouTube playing at the same time. There are also a number of Non-Hangouts 3rd party websites that you can do this (everybody starts watching a youtube video at the same time). Hope this helps, for now.
