Get a dremel or a small small drill bit and slowly drill directly into the head of the stripped screw until it literally comes off. Youll want to push the bit into the chuck of the drill as far into it as you can, so you dont have a bunch of overhang (if that makes sense) Then, once you get the plate or whatever its being secured by this screw off, you'll be left with a litle nub, that you can twist out with needle nose pliers
You need to keep everything very sable when doing this, Ive duct taped a mod to the table before once or even had my roommate help with an extra set of hands. Also I would use masking tape around the screw hole to keep from scratching anything.