My DD has set up a YouTube Channel, which is getting quite a bit of interest.
She's Minecraft & Simms mad & wants to make these videos for her YT Channel too, she's done her first one as a trial, which was just her talking through her Minecraft world & considering she only has QuickTime to record it on, it's gone pretty well -
Though she ended up recording having to record sound & video separately & marrying them up in IMovie, not ideal as our Imovie isn't working properly for some strange reason, but we found a way around it in the end & it worked.
BUT We've hit a problem, last night she tried to record herself & her friends playing Minecraft via a server & Skype - she thought she had a great 15 minutes of video - only to have just her own voice record & no-one else's - she was using a headset with mic, which I did try & warn her could happen & to test first - but you know what preteens are like 
Our MAC doesn't have a built in microphone & things like Frap etc are for PC not MAC:( & I'm presuming that the stupidly expensive MAC equivalent software won't be much use without a mic anyway
Would anyone know if there's a way/how DD can get round this & be able to film & audio record herself AND her friends playing together without losing her friends sound ????
Hope that makes sense
TIA