Many fans of the sport of surfing don't understand how surfers get their scores when viewing surfing competitions. The judges do adhere to a criteria, but this criteria is subjective and is flexibly applied depending on the competition's location and waves being ridden on any particular day.
So if you want to use surf videos to do more than just psyche you up for your next surf - slow-mo the skills you observe to get a sense of the movements being used, simulate those movements before hitting the water, and maintain your focus while in the water. Doing so will allow you to become better faster.
The bottom turn is the generator for power surfing. Develop a strong bottom turn, you develop the capacity to perform strong moves off the top, and with that the mechanism for speed and flow throughout