This is a bit of a can of worms. If you plug an external hard disk into an unmodified Hummy, it will need to format it with ext3 in order to copy files to it. The disk will then not work when attached to your PC because Windows doesn't understand ext3 without extra drivers.
Also, Hummy files (after decryption) are a bit odd and not many media players handle them reliably. That includes MPC-HC. You will probably need to install the free Mirillis Splash Player Lite (or pay for the Pro version).
I suggest it might be a good idea to slow down and spend some time on this forum, particularly the Wiki and the many threads that summarise your options. The things you are wanting to do are exactly what most enthusiastic new owners want to do. There are right ways, wrong ways and better ways to share files between machines. If you don't do some preparatory reading, you will probably spend a lot of time going up blind alleys and you'll then have to start again and do it right. Start at the top of the HDR-Fox T2 forum.