It does not show large icons in Windows 7 Explorer OR Everything (Tool)
AVI and FLV
The Icaros program is not able to fix it.
Of course, I have the Thumbnails show selected in the Control Panel.
All available methods have failed, dozens of different tricks, patches and even registry modification and nothing solves the problem.
When you open a file with several things in it, using Windows Explorer, and click View and select large icons, what happens?
I'm not sure why you mentioned AVI and FLV. I'm also not familiar with Icaros.
When I opened a folder where I store movies and changed from list to large icons none of my flv files displayed thumbnails. (Since I use VLC as my player, all I see is the VLC icon) I suspect that is just the way it is. One avi showed a generic item and the rest showed the VLC cone. Only mp4 files display large icons.