Bring back old Add menu functionality for adding to multiple playlists #3329
Description
Bring back old functionality to add videos to playlists, where it would stay on screen to add the video to each playlist "category" via a checked checkbox before you confirmed your choices. Now we have to add videos one at a time. Their new UI is nice, fancier, and fits better. However, for the functionality, the UX is not as good as it used to be. As soon as you click to add your video to one playlist, the menu disappears and you need to repeat the whole process again if you want to add the video you are watching to multiple playlists. Here is my proposal. Keep the current "add to playlist" UI and change the functionality so that we have to click outside of the window to confirm our choices. Otherwise, we can just add or not add by clicking on the bookmark to indicate highlighted = add video to playlist or not highlighted = video not added to playlist. That would be nice from how adding to playlists used to work.