Mp4 Thumbnails in XP Explore?

[yardline]

I have some .mp4 video files shot with my Sanyo C6. While XP will show thumbnails of all my other video files in Explorer, it will not display them for mp4 files. Does anyone knwo how to fix that?

[jimmalenko]

Without knowing precisely, I *believe* that it is something to do with DirectShow filters - I'm fairly sure that windows can only provide the thumbnail images for files it can decode in Windows Media Player (which uses DirectShow filters).

[yardline]

WMP plays them fine. When I do play one of them it says it's using the "Ulead MPEG-4 ASP Video Decoder" so maybe that's the angle I should pursue. Seems like when I had a fresh install of XP a few months back, Explorer would show the thumbnails. Is there a utility to force WMP to use a different decoder?