Yeah the capo tool is literally just
Start animating the property you want at the current frame you're on.
In the first go i just turned on record and changed the colour at 2 seconds, and it inbetweened between them.
On the second i did the same thing but before i went to 1 second in and turned the capo on so it inbetweened between frame 1 and 2.
This way there are clear breaks between keyframes its not a continuous motion and you can control what happens when easier.
I can give my more complicated examples, but in essence its for control. e.g. I want character's opacity to go from 0 to 1 at 5 seconds in, then i want at 6 seconds rotation to go from 0 to 180 and at 7 i want left to go from 0 to 100. By turning the capo on and resetting it for all 3 you can do all of the above. OR as an alternative you can animate like normal and then drag they keyframes around the timeline but i find that becomes more tedious depending on what you're doing.