Unfortunately that doesn't work. It will snap to either the left or the right side of the symbol, but not the center.
Under normal operation, it will function exactly like you showed in the AVI in that post... but some parts that I have to work on don't operate like that. I have to assume that some random setting is changed with those parts in particular that is causing this behavior.
Even more odd, I have a few files where on Sheet 1, the Datum Symbol feature acts completely different than on Sheet 2 on the same file.
Turn off the Associative option and change it to Point Constructor then pick a random point onscreen then you should be able to drag it. If the dimension moves, so will the Datum symbol, so I'd use the Associative option with X & Y distances from the base dimension or FCF, as shown in the video (near the end). If the dimension moves around during updates, you will probably have to do this again if you keep the origin associative in any way.
