This solution is for all experiencing missing cinematics error while playing Ravenloft Strahd's Possession. I read few posts on this topic but no one figured out why is this happening.

All who own AD&D Masterpiece Collection or Three Worlds compilation as I do have 3 games on one CD: Al-Qadim, Dark Sun 1 and Strahd. All these games are already patched and require no patching. Applying any patch to Strahd will cause cinematics error. It doesn't affect saved games so if you already messed it up just reinstall the game and load your save. Strahd is version 1.2A while the other two games are 1.1.