I'm not sure what he means by 'clearing' his fingerprint, but if you visit EFF[0], you can check if your fingerprint is at least random. I've only been able to achieve a random fingerprint on Brave browser. Even clearing all cookies/cache on your browser will not reset the fingerprint.
To prevent metric collection, you can't be logged in and you need your browser settings set to block cookies for YouTube.
[0] https://coveryourtracks.eff.org/