Backlinks count as external views and don't have as much impact as they do with a regular search engine. The reason is unlike Google where you are searching for something then leaving the site immediately, YouTube wants you to search for something and stay on the site continue to watch videos. External links are not the best way to drive that behavior.
Now there is something to be said of being linked to from other YouTube channels via playlists, etc., but I don't know that anyone can accurately gauge how much that plays into search ranking.
I pointed to that video because YouTube has made it clear what signals they use to promote videos in search and discovery and the TubeBuddy's SEO tools are an implementation of YouTube's best-practices. Creator Insider has posted several videos on search and discovery recently and have never mentioned backlinks as something they look at.