Mac Users/Movie Makers: Advice on filming roleplays?

I am an ESL teacher in China and must give my students a roleplay test this week. My school is slow about support (but supportive), I would like to bypass asking them for help and using my Macbook to record their performances (8×5 min 2 man plays).
I have over 150 GB free in my mac book and also have other small hard drives for storage if this is a problem. Do I have enough room to pull it off? AND are there any other foreseeable issues?