Time is precious, and I’m pretty sure you don’t want to waste it with the average 20 seconds ads for a single videos requested to youtube. This is unfairly exagerate nowadays, but I have a solution:
just type this in your browser: invidio.us
It will shows all the invidio.us instances, click one of these to open a new browser page. Ok, You’ve just landed to a no-ads version of youtube, enjoy.