Good video. I can certainly relate...I've been skiing for 30 years, but only discovered the course 3 years ago.
I am only slightly less beginner than you, but definitely a beginner.
My suggestions (ie, things that worked for me):
First, as RichardDoane said, slow the boat down. When I get my friends started in the course, we go at 26 or 28mph.
Second: Spend some time pulling on a rope on dry land. Attach it about 2.5 feet off the ground, grab the handle and practice a lean. You should have straight arms with elbows on your hips, shoulders somewhat towards the boat (tree, light pole, etc) and your weight even on both feet. Get to know this position well so you can feel when it happens behind the boat.
Third: practice this position pulling away from the wake first. Then, when you feel a difference, try cutting across the wake in this position.
Finally, post lots of video and you will get lots of advice.