To get the thumbs you need to tell the script to look for the video file in the thumbs folder strip the extension and change it to .jpg.
I made a comments on the front page block and did it like this.
I called up bigimage from the db table it had either a wmv or a .avi so i stripped and replaced it with this.
Code:
Content visible to verified customers only.
Then when it came upon an image (thumbnail) with a video extension it changed it
HTH
Sybaris...