I find the podcast app to be comfortable to watch home-downloaded youtube videos - it saves your current location, allows you to skip forward and back by 10 seconds (unlike the TV app) and there's video (unlike the book app).

But currently, my only way to get this done is via itunes (hate it, causes so much issues). Even when I downloaded a random podcast from the app itself, tag editor in CopyTrans Manager gives no "Media kind" selections. Seems like it's just missing as a feature.