@Mattches and everyone else, it’s happening with me as well. It works in private window but not in normal. Normal thing of clearing just Google and YouTube cookies, or even cookies for all sites for all time did nothing. Turning off Shields and using uBlock Origin only also resulted in the same message.
That said, disabling all adblockers or just using in Private only would result in it playing. So yeah, it’s just the next wave of Google’s messing with things. Guessing it’s going to be us just giving it some time for content filters to be updated to address it, once it gets figured out. Or, worst case scenario, we just watch videos in Private for now.
Same issue happens on Chrome when using uBlock Origin Lite. So yeah, it’s definitely just a YouTube/Google being stupid with adblock detection for now.