http://www.youtube.com/watch?v=tZqZgUVDm3c
I wonder if this is caused by him racking the weight on his throat (i.e. the wrong way). When I first starting learning the clean, there were occasions where I would do that and get dizzy within seconds.
As for the kneeling squats videos, they are useful for a lot of people who are lacking in the glute activation department, but I've only known of them being used with very low weights. Though I think Louie Simmons from westside barbell used them as strictly posterior chain work.
I wish I had a video, but there used to be a guy at my gym would do 1-pullup then try to hold there while doing all kinds of kicks in the air... kinda like in the old action movies where there's the occasional scene where the guy jumps on a bar then kicks a bad guy running at him.