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):

1. Click the uBlock Origin icon on Firefox's menu bar
2. You'll see a three-gear icon at the bottom right. Click this to open the dashboard.
3. Click the "Purge all caches" button at the top.
4. 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.