I came across the stickied weekly thread at uBlock Origin's sub-Reddit. WARNING: It's a long and complicated read.
The TL;DR takeaway is thus (especially for those who use Firefox):
Click the uBlock Origin icon on Firefox's menu bar
You'll see a three-gear icon at the bottom right. Click this to open the dashboard.
Click the "Purge all caches" button at the top.
Click the "Update now" button at the top.
Note: You may have to do this several times per day since YouTube keeps changing their anti-adblock scripts. However, the diligent work, from all the volunteers at uBlock Origin, have been able to keep pace. I haven't seen any ads NOR any anti-adblock warnings in the past 48 hours.