These are playlists of videos. If you look in the upper right corner of each video window, you will see a playlist symbol with a pair of numbers separated by a slash (/). If you click on the symbol, you will get a list of the videos contained in the playlist where you can select the subject you’re looking for.
(Please note that these videos were made during beta test of a different version of the tools. The content should still be useful, but you might have to hunt for the new location in the settings panel.)