I'm a sucker for these types of videos. I just unabashedly find it funny to watch videos featuring people mashing up hip-hop or something with something more innocent. My favorite one is the classic: Barney rapping the iconic and vicious Tupac diss track "Hit Em Up" (language is very, very NSFW):

But now, we've got someone doing it and putting way more work into it beyond replacing the audio; he's actually doing coordinated and measured matching. This has to be wildly time-consuming but, hey, it's worth it. Check out below as Bert, Ernie, Elmo, Grover and your other favorites perform classic hip-hop tracks from the 1990s--"Regulate" by Warren G and Nate Dogg, and the all-time great "Tha Crossroads" by Bone Thugs-n-Harmony.

This was definitely the reason the internet was invented in the first place, I truly believe.