Countless groups (frats, companies, volunteer groups, etc.) have done their own versions of the "Happy" video. It's just a bunch of people trying to have some fun in life and I can't fault them for it.
Glad to see they can at least be happy and have some fun making the video! There's probably a lot of other things JWs are expected to do that aren't nearly as much fun.
It's not an official video, so I say "good on them" for having a little fun.