I'm a tall guy (6'3") as I think Frakes is. And notice all those chairs have low backs...probably having to do with prop design. It is actually easier when you are that tall to swing your leg over the back of a chair than it is to pull the chair out, sit down and pull the chair back up. So I bet it actually became pretty natural. When you are watching the clip, some of them are pretty easy to miss because it is effortless for someone that tall.