This Suzuki is a Stunt bike.
Look closely and you will see the protruding black frame tube, the 12'o clock wheelie bar and the extra large rear sprocket. All methods to ease Stunting Tricks.
By the way, there is no Stunt "Mountain bike", you are using a self-made term.
Mountain bikes are bicycles with treaded tires.
There are plenty of "Dirt or Trials" bikes which are not made for any "Stunting" such as is displayed here.
And to all you jealous motorcycle haters, before you hate, educate yourself! This dude is doing stunts in an empty parking lot and display his skills.
Since the speeds are low, the chances of injury are also minimized.