When i watch a video through airplay and quit during the middle of the video i have to click out of the movies section in itunes(like click into my music library) to see my desktop screen again on my tv. sounds like another small bug. I havent had any audio issues.
actually just came across the same issue. I put a DVD in my imac.. airplay mirroring was off at the top of my screen.... dvd started playing but the audio was coming out of my TV..... i opened itunes and airplay was set to my tv instead of my computer... they might not turn off together...