Hmmmm.
After seeing the follow up video I am guessing multiple RX in various areas feeding to some kind of switch/diversity controller.
Shows the pilots all in like a skybox and their goggles appear to be plugged into a video feed rather than using attached CP for 5.8.
Also looks like some standarizing of which quads are used with the intent of making it a televised or internet broadcast. Maybe a standardized field of craft for more even competition?
https://youtu.be/sFHRcW6qnvo
/edit
I also wonder what they are doing for control. Wonder if they have a 2.4ghz to 433mhz relay some place to grant coverage for the areas that 2.4 may have poor LOS or get funky.
My guess is somebody has dumped some solid money into making a reliable quad that can carry enough gear.
The HD video from onboard is likely too high of latency for the quad racing, it is well established that the quad racers like low latency analog for quick obstacle avoidance. So these craft either are recording HD video for later play back and editing, or they are browdcasting their own video live along with an analog lower def image for the pilots to fly off of.
I really need to get into quads for FPV. Been on fixed wing for too long.