i can't believe how good this is, no registration needed, processed a playlist of 500 and 1200 in 2 seconde and ended up with 111 successful result on 133 unavailable videos that were all presented neatly with a button that open a youtube search with the name of the video in another tab, and as if it wasn't enough, some hits have descriptions and link on the creator or where to find it outside of youtube and a page that keep the playlist you searched and result in you web browser local data.
honestly the only improvement i can think of is to somehow being able to do the same for likes and watch later, maybe a plugin that can scrap all videos marked as deleted or private and a feature that can take multiples video url as input to display the result the same way a playlist does ?
anyway, thanks for your work, it made things so much easier !