Once installed, you type a search string in the Settings dialog and then invoke a new menu item under the Window menu. Then the list that you see above is populated with movies from YouTube with titles that match the search string. So, for the above, my search string is "Bill Clinton". Whenever you select a new item in the list, a small thumbnail that relates to the selected movie is shown to the right of the list and the browser opens displaying the movie.
My adventures in the land of IntelliJ are described here on JetBrains Zone:
I also contributed the result (but without the icon that appears to the right of the list, because I created that part later) to the IntelliJ Plugin Repository, under the name "Search YouTube Plugin".
I've learned a lot and, since I only have an evaluation license, I better continue learning a lot because my time will soon be up.