Well, you could try going to YouTube or Google or Bing (maybe using private browsing would give better results), start typing in the search box and see what comes up in autocomplete. That should give you some idea what terms people are searching for. For example, if I type "bulg" into the YT search bar the first few items in autocomplete are "bulgarian music", "bulgaria", "bulgarian split squat", "bulgarian music 2013" and "bulgarian folk music". Of course, you'll want to find something that's searched regularly but doesn't return too many hits if you want to get noticed.