Long story short, you guys (probably) know that I've been doing a ton of video game covers to throw onto YouTube. Basically, I'm more or less in a situation where I need to sign something that says "Yes, I did create this."
I allowed a friend to use the music in a video of hers, which she does have monetization features turned on for. She's not getting anything from that video (presumably due to my music), so that's why I need to claim that I did, in fact, create it.
The catch is, while I did create the tracks that she's using, I'm just ganking other people's melodies and putting my spin on them. Can I still claim to have created it, even though that's the case? I really want to help out, but the last thing I need is any sort of legal trouble.
Simply put, you didn't create it entirely. You don't satisfy the requirements for monetisation. Chance it at your own peril if you like, but for your own integrity (and out of respect for artists everywhere), just admit it's a cover.
Edit: btw, YouTube give you an awful lot of guidance on what you can and can't do if you look through their help section. They've got a video answering this very question.