Changing the thumbnail image of videos

Ok, so Ive got some videos of some shows of the babes that ive edited - however the thumbnail picture of the new videos are the same as the old ones (i.e the first frame of the old video) even though i have edited that out.

I am therefore left with a video where the thumbnail is of a different girl to the girl the video contains.

Is there a way to change the thumbnail image to that of one relevant to whats in the video?

Well I use Media Player Classic to capture a thumbnail of my video's content. All you have to do is play the video with Media Player Classic, and select the "Save Thumbnails" option fron the file menu. That would then give you an updated thumbnail of the new content.