2. Youtube ads.
I've spent all the day on trying to figure out what's going on. It seems that YT app has two types of video players. Default player uses VAST protocol to get ads and we have no problems with blocking it.
The situation with the second player type is complicated. I still don't understand how does it receive the ads metadata (e.g. a video ad identifier). It's just at some moment I see a tracking request signalling about video ad impression and that's all.