"Video can be used to mislead" is nothing new, but I'll still argue that we're watching a very specific new door open. From the first days of high-fidelity video to the recent past, there has never been a time when someone could fake
this type of content.
Faking a clear, unbroken closeup of a recognizable person has never been a serious option before this. Even when Hollywood had likeness rights and massive budgets, it resorted to rewrites and old B-roll footage when actors died mid-shoot. When people wanted to slander politicians, even state actors with Cold War budgets, they edited photos, faked audio recordings, or staged candid, hard-to-see footage. In the modern era of CGI and digital video editing, bad actors still resorted to misleading edits and out-of-context clips. This, though, is 20 seconds of clear, closeup video of an incredibly famous face. And the fake was good enough that even placed in an art exhibition centered on something that never happened, some viewers thought it was real footage.
I don't share the popular paranoia that deepfakes of politicians are going to start upending democracy; there have always been plenty of people fervently convinced by manipulative video, altered pictures, or simple "somebody said so" lies. What's new is the increasing difficulty of proving truth in the most trusted contexts. Validating even a very narrow claim like "at some point in the past, for some reason, the President said this exact sentence in front of a video camera" is increasingly difficult.