Can you post a pic of the video ?
You can also try > Edit > Song form > Unfold.
While it's rendering the video and audio together,
make a copy of C:\bb\Data\avim\AVIMImages as it deletes them after it's finished.
Open the C:\bb\Data\avim\AVIMImages - Copy and see if the still bmp's are correct.

I will try and install Window10 on another drive later and try it rendering video.