Greasy Fork is available in English.
Provides a button to pop out the YouTube video in a separate window.
< Commentaires sur YouTube Popout Button [mashup]
I have sometimes used "Popout for YouTube™" by Justin Force
https://chrome.google.com/webstore/detail/popout-for-youtube/pofekaindcmmojfnfgbpklepkjfilcep
use these+these = vola lol
https://chrome.google.com/webstore/detail/pop-out-tabs-to-new-windo/lhnaddgiebpcecbcmfcjmlhinfpkkjii
https://chrome.google.com/webstore/detail/popup-window/nnlippelgfbglbhiccffmnmlnhmbjjpe