Chrome: If you've ever full-screened a video in Chrome, you've seen the redundant warning letting you know that a site wants to full-screen a video. If you'd rather not tell your browser that you meant to do that every single time, here's how to permanently remove the permission request.
Whenever you allow a site full-screen video access, it gets added to an exception list. You can find this list by opening Settings > Show Advanced Settings > Privacy > Content Settings > Fullscreen > Manage Exceptions. Alternatively, you can just go to this link in Chrome:
Once you're there, pick any of the existing exceptions and replace its hostname value with the following:
This will permanently allow any and all websites permission to full-screen a video. Keep in mind, there is no way to undo this without resetting Chrome.
That being said, the permissions filter wasn't particularly great at preventing abuse to begin with. It only ever appears after a video has already been full-screened, and it usually only "blocks" legitimate videos anyway. If you're worried about a site enabling full-screen mode without your approval, it's probably best to avoid this method. On the other hand, if you're more annoyed that a button you clicked on purpose asks if you really meant to do that with every new site, this should decrease your annoyance a bit.