The best extension ever made for YouTube. It's a shame that YouTube itself doesn't have this ability or anything like it at all.

Cette extension rajoute des fonctions supplémentaires sur YouTube:
● Sélectionnez la vidéo {0} à {1}
● Déplacez après ici (un ensemble de vidéo)

Please add an option to add things to a playlist (if you are in a playlist marking things)

Edit: I mean it would be great to select videos in one playlist and then be able to add them to a different one