Sir, I have yet to meet, work or care for a person with a mental handicap, but I'm offended by your statement.
That's your problem. I know a few people who have mental handicaps and they are not offended by the word when it's not used as an offense (calling the thread ******** is not meant to offend a person but calling a person a dufus is).
That said, the video in the OP is not funny.