[Carlos Silva] "Considering a Flash animation with white background, is there any tool in Vegas to remove white and create transparency? The idea is the same of I tried to GIFF image, but with flash I am looking forward for better results."
If you are creating the flash animation, just leave out the white background. Vegas will import SWF files and play them on the timeline. I show you how to do this using SWISHmax in my tutorial:
How to make an animated title in Vegas using SWISHmax
I assume you could make all sorts of flash animations to use in Vegas this way.
~jr
http://www.johnrofrano.com
http://www.vasst.com 
