First, well I've been able to get ublock origin to just block the pop-up itself, YouTube now has some scroll event override that locks you to the top of the page. You can't view the comments or recommended anymore... Not that any value is lost there but still.

Second, the pop-up triggers a "three strike" system where they won't let you close the pop-up until you disable ublock. That may be easy enough to defeat today, but if YouTube has already gone to these lengths to force you to watch ads, they may eventually stop loading videos altogether until you do.