Speaking of missing the point, you continue to do so. Yes it matters that Alan Dershowitz is such a piece of shit, but he's also obviously as biased as a person could possibly be on a particular subject. He's a Jewish lawyer who's been hobnobbing with Israeli and Mossad leaders for decades, wrote a book called The Case For Israel, and has frequently appeared on television and in op-eds defending Israel 100% without any room for nuance.
If you presented a Bill Clinton argument, he's a different person, and obviously not so fucking biased, therefore the reaction would be different. But if his clip was as clearly absurd as the Dershowitz clip, then it could be called out as such.
The fact that you can't even recognize that the vast majority of Palestinians weren't even born during previous negotiations shows that it's simply impossible for you to be objective. I get why, but the fact that you can't even acknowledge the bias in the Dershowitz video is legitimately disturbing.