If you are looking at the icon column this seems to have something to do with what your default player is, I think.
In the bar above the seach window, you should see a column "type" If not right click on the bar and select "type" from the drop down menu. This column will show the file extentions.
(As a footnote.. You might like to consider searching for mpeg and avi files and downloading the VLC player
http://www.videolan.org/vlc/ )