I think there's a very visceral part of seeing a human face do/say something that puts it in another league from text. Even though intellectually it may be known that both text and video are trivially forgable, I think it will be a long time before people truly start to question video.
Even when people know the source is not to be trusted, it still influence their judgement in some way.
E.G: we all saw the close shots used journalists to magnify a so-so event and make it newsworthy. Yet, when seen one, many still consider it as "news". We all know which politician lied last year. Yet, when speaking again, many still listen. We all know which company abused consumers. Yet, when a new product is advertised, many still buy.
FWIW, video doesn't need to be forged or manipulated in order to provide an untrustworthy or inaccurate portrayal.
It's possible a video doesn't reveal the appropriate context. (e.g. what happened before the start of the video, and maybe what happened afterwards; or what's happening out of view).
That said, that isn't inherent to video. (And, sure, "swapping faces" doesn't lead to a more accurate portrayal).
