As of today most popular adblocking browser plugins do not fully work on youtube, to bypass annoying video ads before actual video you just need to modify link, example:
From:
https://www.youtube.com/watch?v=eCmFis9EBJ4
To:
https://www.youtube.com/embed/eCmFis9EBJ4
The video ads that are in middle of the video are successfully blocked with uBlock Origin.
Not all videos will work as some youtubers tick the option for not allowing embeds.
Hopefully adblocking software will update soon, until then enjoy this little bypass
