In this video I look at how to remove some rounded screws by using everything from an elastic band to a dedicated damaged screw removal bit. The 7 techniques used in this video are-
Elastic band
Impact screwdriver
Damaged screw remover
Trend Grab it pro
Left handed drill bit
Centre punch
Cold chisel

There is no one method that works on all screws and if you get a long wood screw with a rounded head you have not much chance of removing it.