Basically Youtube instead of counting views via actual requests for the videos instead uses a separate call that essentially says “hey, someone watched this video”. All the ad blockers rather than use a hard coded list of URLs to block which would quickly go stale instead use one of a couple different 3rd party lists the most popular of which is EasyList. EasyList decided to block the URL that youtube uses to register views on the principal that it was a privacy violation because it not only registers “hey someone watched this” but also captures exactly who watched it which allows Google to track your viewing habits.
Basically Youtube instead of counting views via actual requests for the videos instead uses a separate call that essentially says “hey, someone watched this video”. All the ad blockers rather than use a hard coded list of URLs to block which would quickly go stale instead use one of a couple different 3rd party lists the most popular of which is EasyList. EasyList decided to block the URL that youtube uses to register views on the principal that it was a privacy violation because it not only registers “hey someone watched this” but also captures exactly who watched it which allows Google to track your viewing habits.