The puzzle, that lead to the private key 8 was easy:

If you watched the video until the very end, you will hear a sound, which if you were able to reproduce the notation it will result in a 99 notes melody with 6 different notes. If you have turned this base6 code into base58check you got the private key. Pretty easy, huh?

No Vegyzz are the first to hide a Bitcoin private key in a melody! Upvote on Reddit: https://www.reddit.com/r/Bitcoin/comments/7hx24d/no_vegyzz_are_the_first_to_hide_a_bitcoin_private/