Google's John Mueller confirmed, despite the nofollow attribute slapped all over links on YouTube pages, that Google does not use links on YouTube for search.
John said on Twitter "we don't use links on YouTube for search anyway." He did add that if you add links to your comments on YouTube videos, some "people will be annoyed if you comment on videos with links to your site."
Here are those tweets:
We don't use links on YouTube for search anyway, but probably people will be annoyed if you comment on videos with links to your site.
— 🍌 John 🍌 (@JohnMu) June 13, 2020
I always add links to my videos but yea, if I see irrelevant links in my YouTube videos comments area, I do try to remove them.
Forum discussion at Twitter.