Sorry. Been working nights. No, we hadn't planned on making any money off of this. Just for fun and to see how it does. I will check out public domain stuff, but somebody also told me that as long as its not for profit I can use whatever. Is that true?
Well, no. Not really.
Firstly, remember- even if you may not be making money on it, someone else might be. If you riff, say, Green Lantern and toss it up on Youtube, it can (and probably will) be taken down because even if you aren't making a cent on it, Youtube is. Plus, parody law is rather vague. You might claim that riffing a movie is parody and the rights holder might respond with "No, you're distributing my movie for free." The judge might rule either way there, but you might end up spending tens of thousands of dollars in legal fees finding out.
Let me use a real life example. The Nostalgia Critic posted a review of a film a few years back. His format is "show clips from the film and then comment in between clips." But the rights holder got annoyed, saying it showed too much of the film. (It was about 20-25 minutes long and there were probably 10-15 of the film shown.) In the end, the review got taken down. The rifftrax of the same film, however, is still there as it didn't use any of the footage from the film. (And also likely because Legend Films has a legal staff.)
Look, it all depends on what you riff and how much. If it's a public performance, you might want to get the right holder's permission. (It's long odds, but sometimes the RIAA and MPAA show up at things. I remember a local day care getting fined because they were showing a movie to the kids and the MPAA considered that a public performance. I'm sure that it had happened thousands of times before in town without a fine, but that's no consolation if it happens to you.) If it's a 8 minute long youtube clip, you're probably fine. Most rights holders aren't going to bother and those that do will just have it taken down. It's just a question of how much legal risk you want to take. Chances are absolutely nothing will happen, whatever you do. But I'm just warning that the risk is there.