I'd suggest you using skype there's a ton of free software that lets you do the same. But honestly, I'd suggest doing a real video for your application to make sure it has a higher production quality.

A lot of times it isn't what you say but how you say it.

I personally use adobe premier and afteraffects to make sure that the intro, content and outro looks tight. You could also use final cut pro but im not an appler person.

i think its important to use a decent film editor so that you can level everyone's sound and make sure that message comes through clearly... but i admit i may be over thinking it.