Jack studied at the National Institute of Dramatic Art (NIDA) course in playwriting and graduated from the Australian Film, Television and Radio School (AFTRS) in scriptwriting in 1992. Though before that he had obtained a degree in Pharmacy from the University of Sydney.
Feldstein was a scriptwriter for many years before, as he puts it, he woke up one morning and began making neon films. In the 1990s he was instrumental in developing series for Australian television. He then went on to be Head Writer for Brilliant Digital Entertainment where he was involved in creating 3D computer animated multipath webisode series which included Xena-Warrior Princess, Superman and Ace Ventura.