it's already been said, but i'll toss in my two cents:
mics would probably solve most of the problems.
in the back of the room, it was hard to hear some of the dubbing over the actual anime-dubs--let's face it: some caine members are shy and speak quietly in front of groups because they are nervous. mics would allow everyone to be heard over the anime itself.
....or i suppose you could go about it another way and just mute the clip itself, although i think the sound effects and music of the anime add a nice touch to dubbing, so i guess mics would be more efficient...