Greasy Fork is available in English.
ytma! automatically converts YouTube(TM), Vimeo, Vine, Soundcloud, WebM, and MP4 links into real embedded videos.
You should be able to see some youtube link converted to a video thumbnail in this page http://www.neogaf.com/forum/showpost.php?p=28215116&postcount=2
Can you provide some tests links ?
I want test you script, but it is difficult to find some links where it work.
Can you provide them ?
Request:
Can you add an little icon near Videos when your script is in action?