The correct answer to the Kick Full from Prep quiz is the skill is Illegal in Level 3. With the skill not being fully released from the bases it does not meet the definition of a dismount, making it a stunt transition. The maximum amount of twisting for a stunt in Level 3 is 1 twisting rotation (Stunts C1) and the amount of twisting in the video exceeds that limit.
Below is an example of a Kick Full from Prep that is Legal in Level 3.
This ruling and explanation are based on the 2016-17 version of the rules dated August 31, 2016.