I've started playing The Witcher 2 Enhanced Edition as I never got around to playing all of the original, and so far there have been spots of blood on three corners of the screen during almost all of the cutscenes.

It's the same spots of blood each time, appearing in the same places, and they never appeared when I played the original version.

Is there a fix for this at all, because it's rather annoying?

I've seen that as well. Not sure at what patch version it started happening with. I do know that restarting the game when it occurs fixes for a while. I think it has something to do with getting into combat. Some strange blood effect is remaining after the fights. Not always but sometimes. Saving and restarting the game does resolve it for a while.

You're simply hurt. Heal thyself and thy screen will clear...