Hey Humanoid, if you do a Raspbian updates/upgrades via terminal, it shouldn't break anything, no. In fact you can do this with the desktop software update; the first button "Update Raspbian" does just that.
Video . . . no idea. Is it possible you can view your videos on a laptop or mac? I know that's kind of a crappy answer, I just don't have a great answer to how to view video on the Raspberry Pi. Is it stationary or tethered or setup with a monitor?