The site's scope only contains video production related topics; having a video tag seems redundant.
I'm pretty sure that tag is a hold over from when the website was Audio/Video Production rather than Video Production specifically. It would be a fairly substantial cleanup effort to remove the tag from all the existing posts and would cause a lot of edit churn unless we had SE do it behind the scenes.
Additionally, I do still think the tag may be valid. Within the broader scope of the colloquial use of "video", "video" traditionally refers to non-film visual reproductions. A film (actually shot on film) is technically not "video" but would still be on topic for the site. That said, even that usage of the tag would make it currently overused as most of the time the fact that a question is about video formats rather than film formats isn't material to the question, but I do think there is a valid argument for keeping the tag on that merit.