One place to search is the Internet Archive. It is a slog but you can find musicians who have release their copyright to their music.
- Hussalonia's The Public Domain EP
- Michael Sandler's Public Squeegee
- DJ Black Guy - Chokehold
- Sol Rezza
The quality will range from poor to "damn, that is kinda, good."
Be exceedingly careful about using the Internet Archive to locate public domain music. I have found works by Ella Fitzgerald that someone uploaded and tagged as being in the public domain. No. Sister Rosetta Tharpe? Nope. Selections from Your Hit Parade? Oh, hell no.
You don't have to use the whole song. Maybe you need just a bit of the song for an introduction or closing theme. You decide.
You should print out the music page and place in your resource binder. You might have to prove where you got your music and the conditions of use. This will not help you if you are silly enough to use a Betty Boop song in your video. The current copyright holder is Viacom.
I still would give attribution to the musician. It is the right thing to do.
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