Are you using a no-CD hack? There is a video during the blessing that the game expects to find on the CD. Playing that sequence with the CD in should fix that.

Did you try running the configuration program and switching to software or DirectDraw mode, and maybe reducing the resolution?

Is your desktop in 16bit / high colour? I have not had any problems in 32bit / true colour, but the game was designed for 16bit and having the desktop at that setting can fix some issues.

Did you see this section of the Divinity readme file?

Quote
Problem: The cinematics do not play well. The cinematics are more like a slide show, block or even exit the
application.
Cause: the Bink player cannot play the movie optimally
Solution:
1) download and install the latest version of the binkw32.dll: www.radgametools.com
2) download and install the latest drivers of your video card
3) on the ATI Radeon cards, setting the monitor refresh rate to 60 Hz solved the issue:
a) right click on your desktop, select properties, settings
b) click the advanced button, and choose monitor
c) set the refresh frequency to 60 Hz, test and apply
4) if nothing helps, prevent the movies to run by deleting all files *.bik from the Static sub folder in Divine Divinity's install directory. You will not be able to see to cinematics, but you will be able to play the game.