Door Knob Lifesaver!

I managed to remove the handle to the exterior door in the laundry room today.  I was going to replace it this morning, but I ran into a hiccup - the plate on the door wouldn't come off!  There is a little thing that moved, but I pushed it in and nothing happened.  Given my propensity to exert too much force on things (and break them), I decided to just hold off for a bit to Google this situation.

I came across a blog that had a perfect description of what I needed!  I'm a bit anxious to go home and try it.  Maybe at lunch...

How to Remove a Door knob that has no screws.

I'm trying to just put something in that's newer... and works.  I think I picked up something like this: