If you simply add a `-` (en-dash) between the `t` & 2nd `u` in the URL, your viewing experience automatically skips all external ads, without login/premium.

Syntax: www.yout-ube.com/watch?v=XqZsoesa55w

This also works for playlists, and auto-repeats.

edit: is this getting downvoted because it works and people are worried this service might disappear should this bypass become too popular..? Just curious.