Very little - but the occasional painful flashes of revelation will do it every time. And recently I have been having more of them in regard to the video business.
Note: it's not a business as such with me. I get paid in model airplanes and home-made curries - with only the occasional injection of cash. Still shooting's another matter, but video is still so new to me that I don't feel I can legitimately gouge wallets yet. However, that day is coming...
One revelation for me has been just how important good autofocusing on a camera is. Mine have only so-so capability, and I have to make sure that I am darned near on focus before I pull the Johnson bar. The newer generations of cameras with the newest lenses remove some of this tension. To this end I will be seriously looking at the new Fujinon 18-120mm f:4 lens when it becomes commonly available. I want to test it out on my camera to see if it will be an improvement.
I also found that the idea of peering into a viewfinder eyepiece while searching for the action was folly - the LCD screens on the back of my cameras were far more useful for aiming. And the most useful of the screens was the most flexible one - the ones that are just fixed at 90º on the back of the camera only help in the blandest of shots.
It is also not much good taking out the biggest rig I could lash up and hoping to film over a long period with it. Weight is real and unless you are prepared to operate off a tripod, you are going to feel it sooner or later. Indeed, lugging a tripod is fatiguing as well - it is best to have minions, lackeys, and henchmen for this purpose. Lightness and stiffness is worth paying money for when you are going to be moving about.
You also cannot ask any camera with an internal microphone to record anything you want to listen to later - it is just abysmal. The Røde people solve this for you by producing a dazzling range of small microphones - as long as your camera lets you plug in, plug in - and watch your sound level as you film. I started with the big Røde Video Pro and moved to the smaller one for indoor work - it seems to do just as good a job provided you do not need to have variable attenuation.
Lighting for video is a huge and unexplored universe, but the time when you don't need as much are the times when the sun looks straight into your lens. The times when you need more, the theatre managers or people in the restaurant deliberately decide to save electricity and light the place with a glow-worm. If you can make your own light, take your own light. It may not be Hollywood, but at least make it bright enough to keep you from hitting the edge of the table with your groin.
Note: the Nikon Z30 in the Camera Electronic cabinet ticks any number of the good boxes here. It also has a Joby Beamo mounted on it which solves a number of the light problems. If you plug in a small Røde microphone you have the vlog or selfie camera you need. The new Z mount lens here is the 16-50 and for the purpose is ideal. The weight is minimal and the battery life more than enough for the travel vlogger. ( But take 2 or 3 anyway... )
It still begs a monopod or light tripod to help with the filming, but that and a small bag would be all you'd need for a good video experience.
