The only thing that makes any sense about this pulling style is that by relaxing the hamstrings into a squat, the low back is easier to get tight since the tension is off the pelvis at the set position. But you pay for this with a lot of bar path inefficiency, as Sagir quite vividly demonstrates as he lays back in attempt to save all of his pulls that go forward due to his floor pull. Many people have become very good at doing things inefficiently, and I'm sure you know of very accomplished athletes who would be even better were they more efficient at their sports. Being elite doesn't automatically make you efficient.
I spend about 2 hours with many videos explaining this in the seminar, so I can't type it all here, although I think you know that I have discussed it at length previously and elsewhere. It's interesting that the video guy, and most Olympic weightlifting coaches, can't explain what is going on here, but anybody who has been through our seminar -- and Tommy Kono, of course -- can.