Quite honestly, I don't need my commuting bike to take a four foot jump, or navigate a skree slope, or handle any of the free riding in that video. I don't know about you, but I commute in a city, the streets are paved, and while they might be rougher than I like, the potholes don't justify 8 inches of suspension.

A mountain bike is purpose built just like a road bike; you can you it outside of its purpose, but it will be sub optimal.