Play that launch back at .25 speed and you can see the rear porpoising bad, unloading the tires. I had a similar problem at Beaver because my shocks were set way too soft.
You can see your launch at 1/4 speed here:
https://youtu.be/IRzrzPM0yVQ?t=1m45sEdit: I tried to set it at 1/4 speed, but I think you'll have to change it to that yourself under the "settings" in the lower right corner.
Compare it to mine unloading here:
https://youtu.be/y5mDOTExE_UIt allows the rear to rebound back up and lose all traction. Only difference I see is that yours doesn't seem to stop bouncing. What shocks and springs do you have on it?
Slow-mo is one of the greatest tools you can have for finding problems with your launch. Keep at it, Howie. Looks like you could knock a couple tenths off when you get it figured out.