He did 2001 squats. Supposedly Karl Gotch once did 9001.
I just did 320 reps in about twenty minutes. The great thing is, even though people are talking about being sore for a week (true), once you get used to them you can Hindu Squat pretty frequently. I do them every other day now.
As far as being better than flat-footed squats, hang on let me try a few.
I get more of a strech in the hips with flat ones, but I feel like there isn't as much of a ROM. Also, my back rounds a bit at the bottom. Chalk that up to lack of flexibility, and I'd fall over if I didn't. But when only using your bodyweight, I'm not sure how much of a problem rounding your back really is.
Hindus involve much more balance because you're shifting your weight.
Plus Hindu Squats involve your calves more, but your quads will crap out long before your calves break a sweat.
Just my 2 cents.