Dronason
Premium Pilot
You are absolutely correct.You have FPV receivers and goggles for 5.8, 2.4 and 1.2/1.3 GHz bands. Almost forgot, the new 3.3 GHz band too, although still rare. But thats not the issue, the phantom sends a digitally encoded h264 video stream. The exact protocol is probably even proprietary/secret.
Fatsharks and the like work with an analog PAL or NTSC video signal. That has its advantages, but its completely incompatible. Almost like connecting a 2.4 GHz wifi antenna to an old CRT TV and hoping to receive youtube.