No more thumbnails on mp4 shortcuts

I found myself on this forum because I had exactly the same problem after an update to live essentials 12. I followed the advice and like other people I could not get the screen shots of the regedit files but I discovered another way. google media previewer and this will change the default icons back to thumnails.
found lots of ways to improve these too by putting the picture of the film on the front like a dvd case thanks to aksz on here

Excuse the necropost but these are step by step instructions for how to fix this as I had the same problem after a Windows Update.


First, go to Start and type regedit to open the Registry Editor.
Then click the arrow next to HKEY_CLASSES_ROOT to open it and scroll down until you see the .avi folder (which is actually a registry key). Click on that arrow to open it too.
You should see several keys, including one named PersistentHandler and shellex. First, click on PersistentHandler and you'll see in the pane on the right that under Data it has one String Value. Under Name, right click that String Value (for me, it was named (Default)) and then Modify and copy the Value Data (BUT DON'T CHANGE IT) and paste it to Notepad under PH for PersistentHandler.

For me, the Value Data was {098f2470-bae0-11cd-b579-08002b30bfeb} but yours might be different.
Now go to shellex and click the arrow next to it to open it. You should see three more keys that are named:
{00021500-0000-0000-C000-000000000046}
{BB2E617C-0920-11D1-9A0B-00C04FC2D6C1}
{e357fccd-a995-4576-b01f-234630154e96}
You need to click each key to show its string value in the pane on the right and copy the value data for each string value and save them to NotePad like you did with PersistentHandler.

Now scroll down to the .mp4 key and open it, then open shellex too to show all its keys. Right away, you should see that several keys (and/or their string values) that .avi had are missing from .mp4. You need to recreate whatever's missing.
So, right click on .mp4, go to New, then Key. Type in PersistentHandler, then right click the String Value, then Modify and copy/paste the value data under PH that you saved to Notepad. And that's it, you've recreated that missing key and string value. Now do the same for the missing ones under shellex, then close the registry editor and that should fix the problem.


Now you either have to restart your computer or restart Windows Explorer. To restart explorer, open Notepad again, then copy this to Notepad and save it as a batch file by giving the saved text file the extension .bat instead of .txt:


taskkill /f /im explorer.exe
start explorer.exe


Now, double-click the .bat file and wait a few seconds, then check to see if your thumbnails have returned for your mp4 videos. And that should fix it! (It did for me.)


Credit to frederic from earlier in this thread for pointing me in the right direction, namely to the registry, though his instructions were somewhat confusing (seems to be French, so not a native English speaker?) And also to whoever originally shared that restart explorer batch file (was it on these forums?), I've been using it for years to reclaim memory whenever I've had to close down my browser and other running programs because my computer was slowing down--like restarting it without having to actually reboot it. Been very useful.