Type of Trick:
Invert / Transition
The performer faces forward and hurdles and reaches for the ground. Right before the hands touch the ground the performer turns there shoulders 90 degrees while kicking up to a handstand position. As the body is completely inverted and the legs are together you continue to turn another 90 degrees while snapping the legs down to the ground and bringing the chest up. If done correctly you will be facing the opposite direction from when you started. This skill is done to build momentum and power at the beginning of a tumbling pass.
Many people believe the Round-Off is just a carthwheel where the legs come together and land at the same time but it's more like a handstand snap down with a half twist than it is a cartwheel.
Find extreme martial arts videos featuring a Round-Off