I've seen similar posts throughout the forum and from what I can tell, you can narrow down your search results by file type after the search has started.

If I wanted to search for certain videos in MP4 format, can I somehow filter search results to show only MP4s? You know, rather than perform the search and then click on the format to filter results again...

maybe with use of the junkfilter or spamfilter you can...dont know for sure