TA, I can tell you this for certain.
Not that I was anywhere near this guy's level, but before I started training legs seriously (with squats and box step-ups for tennis), I could bang out dips and chins like it was nobody's business. I was 6'1" and weighed 157 lbs. prior to seriously training legs.
I believe I was my most explosive and naturally athletic at that weight, although many on this board would have called me a twink.
I am definitely stronger, and was able to be more stable (for tennis) with stronger legs, hips and overall core, but I lost something in the process.
In short, if that guy trained legs with weights, he would not be able to do many of his moves.