may I be the first to say "mmmmademoiselle"
I'll second the trying to focus on the movie too much. But to be honest, that sometimes happens even on the worst of the MST movies.
A strange thing that happened to me: there were dvd files left on my computer after my many attempts at reauthoring that always had a slight problem (audio delay not fixed, riff audio too loud, used PAL not NTSC settings). I finally gave in and just watched it using the RiffTrax player, but instead of loading my dvd, it somehow found the dvd files on my other hard drive and loaded them. It became obvious when the riffs had an echo, and the movies audio/video were out of sync.