Interestingly this will probably mess up google search results as well. There are so many things in youtube that should have been a text post but are videos on youtube (for example how to do something technical), that somehow mysteriously come out as top results on google search. They've been rendered even more useless than they were before. I'm already not willing to sit through a video if it could have been text, but I'm sure some people are. I wonder if a slate of ads before, and during, will kill of that type of content.
Honestly, I consider the existence of such things kind of toxic, which is a weirdly extreme view, I admit, so I'm kinda rooting for these types of videos to get pushed out of the results.