Despite the fact that script for importing screenshots (from kinopoisk.ru) was updated 3 days ago (28 May 2013), it still doesn't work (I suspect there's problem with URL query).
I do not know, wich version you are using, but with 1.0.2.5 copy from clipboard functions very well. Just tested it. You have to be in edit mode though.
Well, there are some scripts for screenshots, but I do not use them. One is a russian version for kinopoisk (ÊèíîÏîèñê.Ru) the other one is filmtv. Both do not work for me, so I decided to do it manually. As I use MediaPortal on my HTPC with MovingPictures I proceed like described in this article http://forum.team-mediaportal.com/threads/mein-weg-zur-perfekten-moving-pictures-datenbank.103039/ (German only). For my home made videos I use the built in functionality to take screenshots from the movie.