I have noticed that there are very few (if any, other than the Wizard's promo) Video Podcasts of D&D sessions. There are sites like that post regular audio podcasts, but I can't seem to find video anywhere. Even video that focuses on the gametable so that listeners/watchers can visualize the situations.

I was wondering if you felt that there was a big enough market for this that one could profit, and if so...how to go about that.

Money would only come from advertising. And dude gamers ain't loaded.

I would think that your only chance for success would be to concentrate on one game system that was popular (Games Workshop comes to mind), then start producing mounds of video and adventures and hope that the manufacturer ponys up. But I really doubt it. There are lots of people out there sharing their own stuff for free.