1- Never even released on VHS, A staple of history classrooms, it's hysterical "Davey Butcher You're Free!" Climax is an ancient meme among all who've seen it. It's like an educational short and movie in one!
2- if it's not oublic domain, it's got to be super cheap by now.
3- has lots of recognizeable stars like Fred Gwynn and Lorne Green.

Also, the actual James Porter has just posted to your forum. Guest riffer! http://forum.rifftrax.com/index.php?topic=26369.0
You can watch it here. https://youtu.be/mfISCCAFXec