I found this line on /ow_plugins/video/classes/video_providers.php
const thumbUrlPattern = 'http://img.youtube.com/vi/()/default.jpg';
Here i can replace "default" with "hqdefault" or "0" and it works, but just in videos added by newsfeed.
I know there is a reported bug about vimeo thumbnails when vimeos are added by newsfeed, thats another topic and i cant find a solution for it.
Is there a way to change that thumbnail url on embedded videos too? Just for vimeo and youtube.
Now i'm changing thumbnails urls by jquery,it works, but is a poor solution.
Thanks in advance.