Currently Being ModeratedDec 1, 2011 4:20 PM (in response to haydiosmeeo)
Keynote 5.1.1 update just came out this afternoon, and it mentions working with large files on Lion. Haven't had a chance to try it out yet, but might be worth a shot. Also, are you running 10.7.2? I know they fixed some video related issue in that update.