Having
just done this (using the method in that video) it is pretty easy. If you get nervous walking around on the roof you can always crawl (what I usually do on top of the cover anyway).
Nonetheless, we're done for the season LOL:
If your cover doesn't have any sort of weight to throw the straps underneath, just get one of these clamps:
Then clamp it on the end for a weight--works like a charm.