Yep, the poster did the classical mix up between "Nokia Photobeamer" and "Nokia Beamer", which are two distinct apps.
Nokia Beamer allows you to share your Lumia display with another device. And it’s the craziest thing we’ve ever seen | Windows Phone Central
Nokia PhotoBeamer is an app to project photos onto another screen through scanning a QR code.
This app here has always been functional for 512MB devices.
Nokia BEAMER is another app that goes a step further and lets you mirror the display of a Nokia Lumia.
This app is the one that ONLY works with Lumias with 1GB+ ram...
So sorry to say, but Beamer is still not available for 512MB devices, and probably won't be anytime soon.
You had it mixed up with "Photobeamer".