The fixture should not be difficult to configure. If you have a specific board post the brand and model. Hopefully there is a manual on the web for your device. If so I will generate a fixture for you if you desire.
If the relays are energized/not energized then there are two approaches to configuring the device.
One is to tell the generator that the device has n channels where n is the number of relays. This appears to be the way the device in your Youtube link is defined. In the channel description window you can label each channel so that it identifies the relay. In your link the relays are named Relay 01, Relay 02, etc. The board will receive the DMX signal the same as any other DMX controlled fixture. The relays will energize / de-energize at whatever DMX level the manufacturer has set.
The other approach is to build the fixture for one channel and then add the number of fixtures needed to control the number of relays on the board. In your link the boards have six relays. With this approach you would need to add six fixtures for each board.
Either way will work, its personal preference.
I saw one board that produced a variable voltage output. The output voltage varies, just as light intensity varies, based on the value in the DMX signal for the assigned channel.
Hope this helps.