The correct answer to the Inverted Low to Upright High quiz is the skill is Illegal in Level 5. As performed in the video, the stunt becomes inverted as it lowers to shoulder level. This makes the skill a downward inversion from above prep level that stops inverted, which is not allowed in Level 5.
The release move itself, starting with the bottom of the dip at prep level, is allowed in Level 5.
The explanation is based on the 2017-18 version of the cheer rules dated August 30, 2017.