Great idea man. Also, this may be harder, but in addition to this, you can have a /keepreplay on/off command. It could help when maybe you just held your hand, and you want to remove it because it just doesnt look right, but since it has happend early, the whole replay would have been screwed up. So this would either just allow you to make that one litle change and then continue the replay as it is, or you could have it off if you want to change the replay from the frame you have selected.
-Obviously, supported