When I disable it the error disappears. Also when I reload the page while it's on, I can then watch the videos. But that's really annoying. Usually the video page with the error will refresh automatically after a while, so I suspect the error refers to the actual ad and not the main video. And after the YouTube has determined that the ad has played (or thinks I have watched it) for long enough the main video gets loaded automatically which of course does not cause an error since it's not blocked.
Interestingly when I disable the Improve YouTube! extension ads are being blocked normally. I use uBlock Origin and Gostery as well.
I'm sure the ad-blockers will be able to bypass it soon.
If you want to support creators consider Patreon. It’s not perfect (it’s got ReCaptcha and Facebook crap embedded in the page but they can be blocked) but still better than handing over your personal details to Google on a silver platter.
There is nothing about a simple text or image ad that is annoying enough to block. Yet they went way further than that, and here we are.