Sometimes video podcasts provide an alternative link with lower-quality versions of the files that seem to work on the tablets but look ugly. (look for "3gp" video feed)

As for performance, my experience is that MPlayer is the best way to play videos on the tablet, although for some formats, the built-in Media Player works better.

Transcoding directly on the tablet is not really an option, as it would - obviously - take longer than the playback. If you really want to do this, you can find out how to write a post-download hook script for gPodder on this wiki page: http://wiki.gpodder.org/wiki/Time_stretching

Another option that I wanted to do some time but did not get around to do yet is to provide a webservice that acts as a "filter" for normal video podcasts and that uses tablet-encode to dynamically convert videos to a format perfect for the tablets, so if you would want to use http://example.com/podcast.rss as a video podcast on the tablet, you could add http://example.org/service/tabletvid...om/podcast.rss to gPodder and that would contain the same content as the original feed, but with the enclosure URLs changed so that a download would trigger a server-side video conversion and then you always have a well-playable video on your tablet, independend on how much bandwidth the original video has.