What is happening with YouTube is that we block their ads and then they find a way to circumvent our blocks and when they do, ads will show until we are able to block them again.
This is pretty much an ongoing situation and our filter list authors check daily for ads and then work on blocking them. For this reason, you may have periods while ads are showing and then they are blocked again. If you are only seeing ads on YouTube and not any other sites, that is generally what is happening.

Regarding Acceptable Ads, we believe in balancing user experience with the need for publishers to monetize their content. They are non-intrusive ads that abide to a series of criteria. Websites have to apply join the program and are judged by a committee. This ensures that all pages follow the criteria established. 

You can chose to opt-out from seeing Acceptable Ads at any time in your ABP settings.