What happens then? 1?

What happens if you watch a video, a series or a film on YouTube, Netflix or anywhere else where you can watch a video, this video is taken down or deleted at the moment you watch it? Do you then get a notification saying "You can no longer watch this series / film / video because it has been taken down / deleted" or can you still watch it to the end and is no longer available from then on?

So for me it was this gray screen with "the video is no longer available" or something like that

I think it depends on the way the video is played.

So there are videos that are completely loaded into your browser's cache and then played. Here you should actually be able to watch the video to the end.

A part is now pre-buffered on YouTube and everything happens live.

So it differs depending on the website's system, I would say.

It depends on how far it is buffered.