Video files not shown in Vista media center
 

Hi, in my Media Center (OS - Vista Ultimate) I do not see video files.
Directory is included in the library, but this does not helps. Video files
are simple ones - like classic .AVI.
Picture files (.JPEG) are shown in the catalogue and viewed properly
Only way to see video viles - on the top of screen "See related videos".
Then all the videos appear and media centers.
Should I do "library reset"? If yes, how to do it in Vista media center?