These work like Back and Forward keys in an Internet Browser. Behold remembers everytime you use a hyperlink to move to some other place in the Everything Report. You can use the Back command to move to the previous place in the report, and once you've moved back, you can move forward again. Behold remembers many steps back. The toolbar items for this command offer a dropdown box, where you can select the location you want to go to.
This command is intended to stop loading files. If you have small files, they will load very quickly and you probably won't have time to use this command. But if you have very large files that take a while to load, you can use the Stop command to interrupt the loading.
Note that it may take a second or two after you press the stop command for the interruption to happen.