dragon,
I had to stop watching that vid because my back started to hurt just looking at it.
I do remember doing one of those leg bends many years ago in a footy game. I didn't have the same expression on my face as she had while doing it.
(dis-colated knee)
Same thing when I tried to bail over the handlebars on my FJ1200 when a windowshopping female (while driving on the wrong side of the road)
headoned me!
My legs certainly dont bend like hers!
Got both of them just below the knees and did the ligaments no good at all.
Hyperextension I think it was called! All I remember it hurt a bloody lot more than a break and took a lot longer to heal!