Geia sou. There is a topic dedicated to this. And on page 2 of that topic (
https://forum.opensubtitles.org/viewtop ... =15#p39399 ) you will see that another Greek person (nickname "orestes1986") is also into it.
You can read some 'guidance' in my reply tho his post. No need for a watermarked video file, a high quality full version is ready for (legal!) download all over the place. See the link in my post right before his.
Maybe it's a good idea to announce yourself there in that topic and maybe do some teamwork with orestes1986 - I understood he can translate, but is not experienced with subtitling specific things. Maybe together you can make something really nice.
Orea