Go with QT 5. It's been out for over a year now. Given the audience I'd say it's a safe bet they have 5 . . . and if they don't, I doubt it's a company he'd want to work for.
I've also got a suggestion. Since audio is 70% of what we see, go with a better codec than QDesign Music. Use IMA 4:1 or mp3, even if you end up with a larger file size. It'll be worth it. Hell, what's another 600k or so if the file is 20+ megs.
Good luck.