Using other people achievements is “awesome” for your marketing.

The legality of “borrowing” a lot of videos from many different sources without explicit credits and requests for permission is questionable if not a plain fraud. The goal was probably achieved – a lot of propagation for Hadouken song, but I would not recommend this kind of propagation to anyone – too risky and unethical too. I would be very offended if mine video was used in this mashup too.