Saw your request today and decided to give it a shot. Took a little longer than I expected but I'm satisfied with the result. Let me know what you think.
https://greasyfork.org/en/scripts/7044-youtube-history-management
Hmm... it seems this script is no longer working. The Edit History button is missing.
youtube doesn't allow deleting multiple videos in history. Perfect thing to fix via US
As in the title. Youtube doesn't allow deleting multiple videos in history. This needs to be fixed.