That's the same moral panic there was about Photoshop, but it turned out that people don't believe tricked imaged without any context.
Photoshop exists because people believe images that have been modified. Pretty much every billboard, magazine cover, print advert, or Instagram post you see has been photoshopped literally because people believe images enough to make it worthwhile spending the time changing it to be 'better'.
Adobe built a multi-billion dollar business on the basis of tricking people with images that aren't real.
The assumption that it wouldn't work for video, or that people won't believe modified news images, is counter to all of the available evidence.
O, well, let me see: because people are more susceptible to believing a video than a picture and some accompanying text when it comes to statements by a person?