An Italian TV program, "Striscia la notizia", has been broadcasting videos featuring very well-known people (here) for a couple of years now, long-lasting videos, fake ones (not to scam, but probably to put those people in a "bad light", to make them lose popularity).
For example, the ex-wife of the footballer Totti (you probably know this one).
Solutions will have to be found to protect people from these fake videos. How? The only thing that comes to mind is some sort of signature; how? Well, probably all videos will have to have a signed QR code.