Script Summary: Adds a direct YouTube link below all YT videos posted on Equestria Daily, Derpy Hooves Studio, Equestrian Rhythm, PonyLeaks, and De Horror!/The Horror!. (Formerly "Equestria Daily YouTube Linkifier.")
Simply what is says in the summary. :)
I wrote it for the purpose of viewing EqD-posted videos on YouTube itself, thus being able to easily add them to more playlists than the "Watch Later" default.
Then I went wandering through more FiM fansites and discovered this could work elsewhere.