"regedit" and delete ANYthing that has "LimeWire" in it.
Use the "Find" option. It should take a while, sorry, but effective.
Eventually you should be able to delete the Data, when the right key "unlocks" the hold on it.
As for the .vob/.avi issue, try research... www.videohelp.com
Check out the green "How-To" section.