Creating videos is a new medium for me, and the majority of my research is learning how to do it…
I'm mostly experimenting within the actual program, but Google helps on occasion:

https://discussions.apple.com/thread/3071186?start=0&tstart=0

http://www.youtube.com/watch?v=sztZB50kW_E

http://forums.macrumors.com/showthread.php?t=1370269
(This was what finally helped in regards to sizing! YES!)