From what I can see, Democracy TV is another client capable of reading podcast feeds. You can podcast video to either iTunes or any other "podcatching" client that supports video. Subscribing to a feed at the most requires that you copy a feed URL (which the module of my suite provides) and pasting it into the client somewhere. Better clients will recognize the pcast:// or feed:// protocols and automatically add when you click on the link.
The Podcast Suite itself can support any file format, but be aware that the people watching the podcast will need whatever software necessary to view them. Quicktime and several other formats are becoming popular for video podcasts. I would suggest avoiding Microsoft's formats.
There are better explanations of podcasting in general floating around:
http://www.ipodder.org/whatIsPodcastingAnd to reiterate, the format of the files doesn't matter as long as your audience can view them.