The white "cloth" you see is actually athletic tape. My son, who has Osgood-Schlatter's, puts two layers of tape under his patella during the summer and wears knee braces during the winter. He tried kinesio tape as well, and he really enjoyed it until it irritated his skin. It's not what you see on their knees, though.
EXO3 Tour 16x18, BHBR 17 @something sub-40