The old trick of pressing Control+End, then shift+2 (to go back to the previous heading level 2), still works to find comments.
However, Youtube is taking longer than ever to show comments now--I just had timings of 3 seconds on one video, and 15 or so on another, before the Shift+2 actually worked.
However--I might test this more--if you pause the video (by hitting K, or NVDA+F2 then K), then do the Control+End, Shift+2, that may load the comments quicker. It seemed to in one test I did.
I don't generally use Youtube by computer, so YMMV, but these were my results in Firefox just now.
"In this life there are obstacles, and forces who overcome obstacles. You can be either one or the other.
If you refuse to even try to clear an obstacle, you become the obstacle."
- Joel Shepherd