I've had the suggestion to remove the voice bit more than once for that track, so I think it's time that i do so and offer it as an alternative version. I will do that and link dump it on that video as soon as I get home tonight.
The Jingle Bell Rocks track I took the guitar chords directly from another guy's tutorial, who had his video monetized, so I'm not sure. I hoped that I put enough of my own spin on the song, with the brush drums and the bells, that it would be unique enough to pass muster.
As for the They Might Be Giants track, I did the instrumental around an acapella track done by Molly Lewis (sweetafton23) having no prior knowledge of the original song. Some might call that blasphemy, but I liked the results of it.
And as far as using my music, I don't really require anything from people to use my music. I've looked around at what other people have done with their music, and it seems that while most people are nice enough to ask and also credit you even if they don't ask, people are going to do what they're going to do, so there's no sense in trying to enforce anything. You're all free to use my music whether you credit me or not. :)
In any case, I'm trying to expand my audience into international by doing multilingual translations of the most relevant meta tags on my videos and channel. I just did this recently, so I'm waiting to see how it works.