Question:
Can KDS-7 stream video through different VLANs?

Answer:
Yes, this is supported.
KDS7 uses multicast (default) for discovering, streaming, use unicast for part feature or control.
It is possible if the network allows the multicast forwarding between different VLAN. It requires a L3 network switch.
A network expert is necessary in such project.

Overview
The KDS-7 family encoders and decoders by default use multicast as stream forwarding. This document is used for listing all multicast addresses and all used port to IT administrator for configuring the network.