Well, yes, of course it's different from an MP3. Part of what makes podcasting possible is RSS. If I upload an MP3 to my website, that isn't the same as uploading an MP3 and publishing an update for it to an RSS feed monitored by individual subscribers and podcast services.
Eh. If I make short documentaries in MP4 format and only distribute them in RSS are they podcasts? If I'm a musician and make music videos through RSS are those podcasts?
In other words, is any 1+ set of media files on RSS a podcast?
If you publish them to a podcast-compatible RSS feed, yes, of course, you are podcasting. There are plenty of video podcasts.
I know a lot of people conflate "podcast" with "show." Just publishing a podcast feed of your songs might not be something you consider a show per se, and that's fair, but if it's a podcast feed I can subscribe to in my podcast player, then you are podcasting.
