Meh, we view "volunteering" differently I'd say.There are many volunteers at every AFL club who do plenty of work for the love of the club, or to get a foot in the door in the industry. It is incredibly common and Melbourne have done zilch wrong, especially in the climate of soft cap expenditure being slashed, in advertising for volunteers.
It being common or legal doesn't make it right. If I was Melbourne I wouldn't be hiring people for that length of time unless I was paying them. That's just me though.