There are two different directions for "upgrade". If you want better FPV, you use a video camera and video tx/rx/monitor setup.
If you want higher quality, you typically go for a GoPro. You can go both directions at the same time, and use a GoPro with a video tx/rx/monitor setup.
Only trick for the FC40 is to use a 2.4Ghz (or anything other than 5.8Ghz) frequency setup. The big thumbscrew mount is a standard GoPro mount,
although you'd typically replace it with an anti-vibration bracket.