I like to open multiple tabs on what I'm going to watch next, and Freetube is a bit clunky with the window management (I wish they had tabs!). So far uBlock has been doing an impeccable job...but these days I can see it struggling a bit more. I can see youtube REALLY tries to give me an ad first, sometimes when you open the video, you can see the first frame of an ad instead of the thumbnail while it starts buffering, then it skips to the video. The ad is not shown, but the first frame of an ad sometimes escapes into the video while it buffers at the beginning, for a second.