Didn't happen to me yet. I've clicked off a bunch.

No, what happens is that a timer is added before you can click the X to close the pop-up. If you continue to close it, video playback will be locked until you disable your ad-block (or circumvent the detection).

That seems unlikely. I can see them blocking you as long as they detect ad block but not banning account / IP wise. It would lead to many non-tech people to be banned without understanding why and those are majority of their viewers who are easiest manipulated into watching ads.

Don't login then.