Well, there is software that will do motion tracking for you, but it is typically only found in high-end packages, like After Effects Pro. Typically though, you will want to place a marker of some sort on the wall while you are filming, then you will have it for reference to get the placement of the scorch mark, or whatever effect you add, more accurate.
As an option, I did just become aware of a very reasonably priced motion tracking program called Magnet
, available from Ex-Cinder. I've not tried it yet personally, but you may want to check it out. EDIT: I see you are on Windows, and Magnet is Mac-only.
Last edited Thu, 5th Apr 2007, 1:09am; edited 1 times in total.