Not from a YouTube video.
All creative works are automatically copyrighted upon creation. It's advised that you register a copyright on the work with the USPTO so that you have official documentation of ownership and the date of creation, but registration isn't required.
So if you see original content on YouTube and use it without permission, you're still violating copyright laws; it's just a matter of whether the owner can prove that they're the original author without a copyright registration.
At any rate, the YouTube video of this kid was likely a copyright infringement in and of itself, as I doubt he obtained the appropriate mechanical license to make use of the underlying composition and lyrics of the song. Nor does it appear that he altered anything enough to make it a new work separate from the original.
Sucks that the guy ripped the kid off, but the kid wouldn't have any copyright infringement claims that I can see.