Anilos.com has exactly what you are looking for.
Aniloscash.com offers Flash FHGs with thumbs that match the clip. Each has high quality picture thumbs OR "screenshot" thumbs for each gallery. Screenshot thumbs will give you an image that is taken from the clip, matching it exactly.
http://galleries.anilos.com/mgpbig/n...=1&l=1&t=1&n=1
We also have long FLVs (2-4 minutes) with a matching JPG.
Drop me a line and I can help you get started