Would love some input on what I can do to correct this issue. Whenever the weight gets "heavy" I start jumping further and further backward - like close to 10-12" back. I don't see this happening at lighter weights at all, just when I start to approach heavy weights. This happens on both cleans and snatches but is most pronounced on snatches. Below are a few vids from yesterday. My PR is 80kg; these lifts are at 70 and 75, respectively.
Sn @ 70: https://vimeo.com/39954195
Sn Pull + Sn @ 70: https://vimeo.com/39954196
Sn (miss) @ 75: https://vimeo.com/39954353
Sn (miss) @ 75: https://vimeo.com/39954352