Sorenson Squeeze is what I had been using on Windows to create the
video clips on the site. The SQZ save files from the Windows version do not open properly on the Mac version and what you will have to do is drop the SQZ file on a text editor ( you will see an XML formatted project settings) and edit any paths pointing to a drive letter - so "D:\movies\japan.mp4" should be pointing to a volume instead.
What I do is to squeeze a file into FLV (FLash Video) format and read that file into a player which I created in Flash - have a look in the Video Clips section to see what I am babbling on about.
There is an annoying thing about Squeeze and that is not having the ability to fade out a soundtrack - it allows you to lay an mp3 soundtrack on top of a video but you cant fade out - why?!