I think most people count the implicit assumptions a universe makes as canon too, e.g. that Criminal Minds and CSI do not have hidden magic because they are procedural cop shows, even though in plenty of urban fantasies magic is not known by everyone either. The only instances where I have seen that kind of thing not labelled AU was in crossovers, because it is canon integration that leads to the premise shifting.

So you wouldn't call a story that works with everything we saw on screen but twists CSI into some kind of urban fantasy and has for example Nick Stokes secretly as a shapeshifting dragon who hid that fact from his colleagues AU?

I can't really say anything about vids because I watch very few, and usually I don't understand them, unless they are either funny or have a very clear story.