It’s the main one I know about that allows mpeg format. The others mostly appear to use MP4 and FLV files. I think there are better players than bubblecast, but if you can’t convert the files to something else it may be a good choice.
You could use the FLV Player or Flowplayer. You won’t be able to escape flash for a while. Just post the video + a link to download.
If you’re wondering why I’m not suggesting using the HTML5 approach: it’s a mess. None of the major browsers support any one format. Firefox will only play OGG Theora. Safari will only play H.264. Google Chrome will play both formats, but it has a very incredibly small market share.