Answer:
The photographers apply the grease in a tripod at the upper part of the leg thread.
Step-by-step explanation:
The photographers use to apply the grease at the upper part of the leg thread while cleaning the tripod. A little goes a long way - and if you put too much, you'll just end up having to wipe it off later. We put a little amount of grease on the threads and then screw the leg segments into place slowly - screwing them in and out a bit as we go to help spread the grease around the threads.
The pieces should turn smoothly if you hear a rough grating sound as you put the pieces back together, check for junk in the threads. You have to do a better job cleaning. You'll need grease in all the moving parts - there's no need to grease screws that should remain tight.