Splunk App for Web Analytics: How to exclude images from a search, and how can I search what organization an audience is connecting from?

So, looking at audience, I can see where they're connecting from etc - is there any way to see what organization, say, stanford.edu, and sort by universities or .edu addresses? Also, is there any way to exclude images and other filler files from a search and just include .htm/.html and .mp3/mp4 files, so I can quickly see which actual pages are most popular and not see that all the first-page images are the most popular things on my site? thanks.