...without making picture filled with unknown colors?

Had you tried doing this by hitting F12 key?
It will make a screenshot of gamescreeen, but not when there is a movie playing, or slideshow running.
If you already tried this, and you have some technical problems - like strange output in screenshots, then refer this question to this forum/ Maybe it can help.

Ну когда люди поймут что у него просто нету русской клавы. :)

Помимо F12 можно ещё поставить прогу для снятия скриншотов типа Hypersnap.