The problem is in windows of course
I have k-lite codec pack from the time when i don't have Splash
Run Win7DSFilterTweaker.exe then open "preferred codecs" > You have too see something like that

Changed all file types on ffdshow from M$ ( or this u have not have Thumbnails or u want )
Then remove splash association from file to none. Restart or Relogin
And they are here, associate avi files again to splash