It's a hinge joint, as knees and elbows often are, though they're ball joints equally as often.
You might want to go with Future Floors if you're not sure about how much to use. FF is less effective at tightening overall, though it still does a very good job mind you, it's also easier to get rid of by working the joint. Nail Polish is a few steps up from FF, and obviously super glue is for emergencies only.
Now, as for how it works, it gets into the joint and dries there, creating some extra material inside the joint and producing extra friction.
Take a small paint brush, with just a little bit of your tightening solution of choice, and put it on the joint, working the joint slowly so as to get it to work its way inside. It make take a few applications if the joint is very loose, but it'll get there.
MisterFanWank shows off some use of FF here:http://www.youtube.com/watch?v=FEcxpBgmdXU&feature=plcp