Synchronize embedded YouTube videos

demo: http://testing-together.herokuapp.com/

I wanted to hear your comments on the following concerns:
a. When a person decides to load another video(ex. he could choose to play another video from the recommended list of videos when the first one ends), should I synchronize it too?
b, When a person joins a channel while a video is playing, should I synchronize his video automatically? For now, only if any of the people who were already in the channel plays, pauses, advances the video, the new visitor would have his video synchronized.
c. I am still using a global variable dontPublish to prevent a loop. I should probably replace this with some other flag, right?
d. How should I deal with dynamically embedded youtube iframes and reinitialize() ?