Using ANY buttons on the RF MX450 sans some sort of setup of it and the PC/MC was counterintuitive. But because you asked if I tried it. Pause and Play were simply used as examples of trying it.
It didn't makes sense to me to try the MX450 that issues a RF signal to work with my out-of-sight Windows PC/MC; especially when those buttons are active or not, depending upon what equipment I have them related to in submenus. But I tried pushing the Pause & Paly buttons just to see if anything happened as you asked.
Because my upstairs Logitech Harmony Companion remote just worked with MC, I wasn't sure of the technical aspects involved. So to me, and in a very general sense of the word, it was magical. Usually, I attempt to understand the background processes involved in something like the Companion remote working with MC. But since it just worked, I was a happy camper and didn't bother digging into it further.
BTW, I'm using an elcom bluetooth trackball with my PC. I was able to set one of its buttons to Pause & Play. So, with or without that 1-button press, it will do what I need to manage MC. However, I was hoping to do away with it and just use my MX450 in Theater View, like I can with my Harmony Companion. But if it's not to be, so be it.