I'll try and keep this short and simple since it's past my bedtime, so I apologize to any purists out there if there's anything I left out. Balanced audio is audio with three wires- hot, neutral (or return) and a ground; most commonly it is used in professional applications (such as with the TV satellite truck I operate). Unbalanced audio is consumer stuff- in this case your mic probably has two wires and terminates in some sort of mini plug. Get the appropriate adapter and you will be just fine. You will probably never find a mini DV cam with balanced audio- that's reserved for professional formats, such as Beta, Beta SX and DVC pro.
Val