They've known about Biden's mental state for many months, even though they were calling the videos cheap fakes. Now, it's impossible to hide, so they have to pretend this is the first time they've worried about his mental fitness. They can't keep up the act, now. It's clear that if Biden had somehow made it through this debate looking half way credible, they would have kept up the charade that he's mentally capable to be president. It exposes what liars they are, for all but the most indoctrinated to understand.