Yep you are 100% spot on as usual. That looks the case. Leaves a small gap on the right hand side and when you scroll up and down quickly then, the page is slipping.I think I might see the problem. The black tabs navigation bar near the top of the match threads (the one with "Discussion", "Match Stats" etc) appears to be too wide leaving a gap on the right of the page.
Does that match what you're seeing?