Much like UDM#2 stated above, RTSP is a great way to isolate those two streams.
It would allow the Genetec system to make the changes VMS systems love to make to camera settings, and still allow video to be transmitted to the second network uninhibited.
If network 1 and 2 have no overlap of IP addresses, and the VPN is set up correctly as many have stated above, this is a very achievable goal.
Network diagrams and discussions with IT departments from both sites are critical, and should be done multiple times before a deployment is ready. The amount of traffic generated here via a VPN cannot be overlooked, and bandwidth calcs done with roughly a 15% overhead addition minimum.