I didnt have Bink Player. So I donwloaded it and instaled.
It is useless because both games uses standalone versions of Bink Player (binkw32.dll) - you can see this file in a Gothic\System folder. Attempts to replace it with a newest version (for example, v1.8i from Gothic 3) causes missing sound of videos.
I also edited gothic.ini file so the scalevideos is now 0, but the videos still dont show.
Hmm, that's strange. Are you sure that you have modified a proper Gothic\System\Gothic.ini file? For example, if your game was installed into Program Files folder, then OS may substitute to editor a virtual copy of ini-file instead of real one (files an folders virtualization feature).
In that FAQ it says something about disabling Anti Alising. I found it in my Catalyst, but couldnt find complete disable option, only slider from performance to quality.
Hmm... I'm never used an ATI videocards and never tried to force Anti Aliasing feature via driver settings.
Another solution I found - Dont use Windows 7...
Well, it already the most extreme case when no more tricks helps to fix problem. Actually by additional tricks and shifts (so-called "dances with a tambourine") you can force to work the majority of old games and on a new OSes.