When its acting like it slipping when he floors it is this from a dead stop, and just mashing the go pedal? Or is he torquing it up and then launching?

I wonder if it may be the converter flashing to its max stall if its just a full floor from a stop?

In my car if i didn't torque up against the converter before nailing it it would flash stall, and sort of seem like it was slipping. Not sure if his is the same problem.

So heres another