I am skeptical. To be able to catch the muzzle blast like that you need a camera capable of shooting a very high frames per second......like at least 240 fps or greater. Very few people have cameras that are that capable. The new model go pro is but it wont shoot the framing like this video.
I doubt the person in the video had a $9,000 video camera.
My opinion is this is some lefty who is anti-gun who tried to make a video to make gun owners look retarded.
I call fake.