Hi Jellygoose,
I don't know exactly what the reason is, but it could be the frame you stop at that moment ( I, B or P frame.)
The way I compare two files, is that I create an .avs script to load both sources, and then I stack them vertical. This way, when you scroll in Vdub, and you do a "Copy current frame to clipboard", you take the identical frame from both streams, and paste that into Windows paint. Then you can compare both. I use something like this:
Code:
clip1 = avisource("k:\source_1.avi")
clip1 = clip1.Subtitle("Source 1 title")
clip2 = avisource("k:\Source_2.avi")
clip2 = clip2.Subtitle("Source 2 title")
StackVertical(clip1, clip2, clip3)
Levels(0, 1.5, 255, 16, 255)
ConvertToRGB()
-kwag