Yes, actually it would be listed as work/paid. I placed my hours in paid observation on the PTCAS application. On non-PTCAS applications I stated it as hours worked .
From what I've seen, most programs don't care whether it is "volunteer" or "paid" hours, just as long as you have observation hours. But erring on the side of caution: check PTCAS and the requirements for the programs you're interested in applying to to find out if they make a distinction between "paid" and "volunteer".