You have to add
to the onlinevideos.xmlCode:<Site name="TvGorge" util="TvGorge" agecheck="false" enabled="true" lang="en"> <Categories> </Categories> </Site>
and copy the dll to C:\Program Files\Team MediaPortal\MediaPortal\plugins\Windows or whereever your installation path is
put your square png in your Team MediaPortal\MediaPortal\thumbs\OnlineVideos\icons, and the 3x1 in Team MediaPortal\MediaPortal\thumbs\OnlineVideos\banners, and you're good to go!
its not working for me. I do have to overwrite the old dll? I just pasted the text in the xml with editor at the end of the file, right?
Yes, you have to overwrite the old dll, because in the xml there is a reference to a (new) class in the dll.