I don't engage with BE (the youtuber here) but I can attest to Bernie being a liberal Zionist, he has consistently voted for more Israel funding, he avoided calling the genocide a genocide until the UN said it is one (even though multiple experts already said so and we could watch it live), even when he accepted it's a genocide he still tried to focus on the rhetoric that this is all Hamas' fault and he only opposes Netanyahu, not Zionism as a whole.
GDF made a good video on the topic called The Bernie Sanders Betrayal. I'm not a fan of GDF because he believes the tail wags the dog and overlooks evidence pointing in a different direction, but that video is good.