The NX300 doesn't support running from external power, you only can charge the battery when off, or run from battery, even when plugged in. The NX500 can be use

The NX300 doesn't support running from external power, you only can charge the battery when off, or run from battery, even when plugged in. The NX500 can be used as a HDMI or network streaming camera, but I'm not sure which protocols it's using for that.