YouTube2NoCookie
Here a 2 bookmarklets to convert youtube.com links (or the short version youtu.be) into their youtube-nocookie.com versions. My daughter uses a Chromebook, but because she's under 13, all YouTube links will open in YouTube Kids and a lot of videos she is allowed to watch aren't available on YouTube kids. With these bookmarklets she can watch them.
You can use the bookmarklets by dragging them to your Bookmarks Toolbar
Convert one url
This bookmarklet asks the user for an url, converts it and opens the video on youtube-nocookie.com
Convert YouTube
Source on Github
Convert all urls on page
This bookmarklet searches the current page for YouTube urls and changes all of them into youtube-nocookie.com urls.
Convert All YouTube Links
Source on Github
Disclaimer
The code for these bookmarklets works for me. I didn't test it in all browsers and all variants of YouTube links or embeds. Use and adapt it for your purposes if you like.
It is not intended to bypass cookies on webpages. If you visit a page with normal YouTube embeds, cookies already have been set.
The convert all links bookmarklet does not work in Gmail except if the account is from someone under 13 😉.