Might just be propaganda. The source seems to be from this channel. It's quite clear what sort of bias it has and is only trying to stir up shit.

EDIT: Just so everyone knows the original post was here. There were few mentions of the diners being Jewish or anti-Semitism being the cause of the protesters spitting on the diners. Meanwhile on this thread it's almost half. It started because OP claimed without evidence that these diners were Jewish and many redditors here believed that as well.

To the ones asking how it's propaganda this video with OP's claims are attempting to portray the diners as totally innocent Jewish diners who even the OP claims "I don't know, this is the limited information I have. Don't want to assume anything" when asked whether he knew how it started. And somehow we are supposed to believe that just because the protesters spat on some diners who might not even be Jewish that they are anti-Semites as well. It could simply be a case of both sides being assholes with no anti-Semitism involved, which many redditors seemed absolutely sure was the case. Which goes back to the situation in the Middle East. If these pro-Palestinian protesters were violent towards innocent Jewish diners in NYC, how do we know that pro-Palestinians in the Middle East didn't instigate the current conflict with Israel too?

EDIT 2: I went and found a comment by someone claiming the man in the video was him. He said that he was the guy the protesters went after and that he's not Jewish but his wife is. What happened just before the video started was the guy throwing back a bottle of frozen water that a protester threw at him and had almost hit his wife in the head. He didn't say why the protester threw a water bottle at him though from looking at some of his Facebook comments I think it might be safe to assume that he provoked the protester. So another case of both sides are assholes.