What a mess. The customer should not have left without his change or his receipt. Without those things he can't prove anything. Too bad he didn't videotape the exchange with the clerk.
I do hope he gets good viral play on his complaint. It would be great to get locals to boycott the store in support. Maybe the next gay person who tries to do business at this gas station will document their experience. Then there's corroboration.
But honestly, on the basis of what his YouTube video alone presents, there's no case. I can't see the gas station owner taking any action whatsoever. Sorry to say.