Windows Explorer Doesn't Display Certain AVI & FLV Thumbnails

I’m using Windows 7 Starter 32-bit. My Windows Explorer can display thumbnails perfectly fine, EXCEPT for a few files. Some FLVs and AVIs have thumbnails, while some others don’t.

It’s not an issue of a slow CPU or bloated RAM, cause I’ve waited and waited, but some thumbnails are still missing. I don't think it's an issue of missing codecs, either, cause they can be played fine (I’m using K-Lite Mega 7.8.0 - 4th October 2011). So I decided to check these oddballs using MediaInfo, one by one.

For FLVs, all of my files come in two formats:

1) Format: AVC, Codec ID: 7
2) Format: Sorenson Spark, Codec ID: 2

Some have thumbnails, some don’t. All were downloaded from YouTube via KeepVid.com. The only pattern I see is that all videos from before January 2009 had thumbnails, while almost all videos downloaded from then till the present (October 2011) didn’t.

As for AVIs, the problematic ones are:

1) Format: MPEG-4 Visual, Codec ID: XVid
2) Format AVC, Codec ID: AVC1

Again, it seems random. There are other AVIs encoded with AVC1 which had thumbnails. So... What might be the solution for this? I’m stumped.

I found another post with the same problem as me, but nobody replied to that:

https://www.sevenforums.com/software/...avi-files.html

K-Lite comes with the Codec Tweak Tool. Anyway, I ran it. There was nothing to fix.

Uninstall Klite, install the Shark007 Win7codecs

After installation, open the settings application using a rightclick on the shortcut and choose Run as Administrator
If UAC is disabled, use the [Reset All] button on 1st use. This is automatically ran if UAC is enabled.
On the Help TAB, use the button to associate filetypes to the Windows players

All files will be thumbnailed with colourful thumbs (not just black) and play properly too.
The Windows explorer Preview Pane will be enabled for use by all filetypes.
If you do have any problems with playback, try the [x] SUGGESTED settings checkbox.

Hahah! After all the hassle of uninstalling K-Lite and then installing Shark007 (and of course, following your instructions above), the FLV thumbnails are still not generating.

But the good news is that I somehow felt like renaming the file extensions of the AVIs (since they were in a folder with MP4 files downloaded from YouTube, I tried renaming them to either .FLV/.MP4), and it worked! =D So it was just a case of wrong containers, I guess.

I also renamed a few Sorenson Spark FLVs into MP4, and the thumbnails appeared. Now, the only thing left is the AVC7 FLVs. Renaming them to MP4 doesn't do anything. What else can I do?

I would venture to guess that they do not have correct extensions (flv). Use the button on the Misc TAB to analyze a media file - that will help you decide what he extension should be. If you're unfamiliar with the contents of the analyzation report, post the information from the tool here and i can tell you what extension the file should have.