I have a hunch I'm the last to know about this, but check out Trailers From Hell. Directors of a mostly cultish nature, giving commentary over trailers of Psychotronic films that influenced them. On the negative side, there's a lot of Eli Roth. However, there's alot of Joe Dante, so it all balances out. (To be fair, the Roth stuff I've watched is actually pretty good.)
Be cautious though, there's loads of spoilers in the commentaries, though you can just watch the trailers as they are.
Here's a good one, where the director of Shaun of the Dead discusses Danger: Diabolik (aka the source for the Beastie Boys' "Body Movin'" video.)
Joe Dante nails From Hell It Came:
PS: dunno if it's just me or my connection, but the trailers really stutter on the streaming.