All other things being equal, silver plating conductors can be advantageous when transmitting signals like HDMI that have high frequency components due to skin effect. You can read up on skin effect on wikipedia if you are interested. The plating will only make a difference if you are right on the ragged edge. If might allow the cable to certify high speed for an extra foot or two, if that. If you can find a certified high speed unplated cable in the length you need, there is no need to go to one with silver plating. It might be advantageous if you need a length longer that the longest certified high speed cable available. Then cable features may start to become important. The usual caveat applies. If you aren't getting sparkles or worse with your current cable, changing cables won't improve the picture.