Greasy Fork is available in English.
以新分頁或新視窗同時播放多個影片或聊天室，並可將任意項目放大置頂。
< Обсуждения: YouTube 多重播放器 YouTube Multi-Player
This approach was indeed considered in the past, but it was abandoned at the time due to performance and technical reasons.
Even now, I cannot guarantee that this can be achieved without affecting performance. Perhaps one day it will be changed to enable scanning with a switch and allow for video selection.
and i did, why not.
Dragging a link to the toolbar is a bit tricky. Maybe someday you'll consider adding a button for this that appears when you hover over a link with a video.