Dear friends: I am having problems with using SWF files in Vegas. Some SWF files work fine and other SWF files do not want to play...They look like a simple picture(although they play in a browser)
It's related to how Flash 5 and later versions insert metadata that makes it so Vegas can't read. I don't know what would be involved in stripping out the metadata, but that's the reason.
I believe (not using Flash) that you can make files be Flash 4 compatible in later versions? I use Swish and Coffeecup, so not sure.