I use an Android device (my tablet, but a phone would be the same) to play videos related to courses while taking notes on my laptop.  It's a great system, except that the controls for your media player are tiny and hard to get to when I need a quick pause to catch up on my notes.

Other media player apps have support for universal play/pause keys over Bluetooth, and this would be both straightforward and a simple solution.  For an example of how this could work, I have earbuds with a built-in pause button.  I could just tap my ear to pause/play the video (and to adjust the volume.)  Other people use a hand-held media controller for Android the same way.