Y'all know what Darias Khondji and Dean Cundey, Kovaks, Carpenter, Storaro, Toland, Conrad Hall, Harris Savides and pretty much anyone you can think of and dozens you can't, guys who shoot great looking stuff on purpose, not by accident, not because they got lucky but by design and through their own effort and expertise, either for the selfish benefit of the image itself or in service to the story, you know what they did so that they could do that stuff when it count, when they were getting paid to do what they did, when dozens if not hundreds of people were depending on them, waiting on them, when possibly millions of dollars were on the line or potentially rendered forfeit, you know what they were doing so that they could do what they did?
They were shooting tests.
Every camera. Every lens. Thoroughly. They didn't waste other people's times learning what they could and couldn't do under a variety of common or unique circumstances on-the-clock. They're smart enough to realize the occasional "happy accident" of a flare or focus pull or color combination or Golden Triangle configuration that just happend to occur at just the right time such that a most amazingly emotional chord is struck when the image is viewed by most humans is great but discovering that that last take, the one where the set/car/character/town is destroyed by fire, the giant monster is blown up, the command shuttle breaks apart the rented helicopter is finally, perfectly aligned with the setting sun to create a perfect silhouette through rippling heat refraction in some exotic locale on their last day of access or visa or the last raw nerve of some local potentate or executive producer isn't wasted because they didn't know WTF they were doing and just hoping for the best.
They weren't satisfied knowing the stuff they were using was expensive, or from a well known pedigree, or supposedly crafted by Santa Claus's most talented, clever elves, or promised in some way to never fuck up, under any circumstance, with any other combination of previous, contemporary or future widgets made by Satan Claus or the Easter Bunny or Baby Jesus. They had to know. So they could do it. On purpose. On demand. Repeatedly.
They shot tests.
What they likely didn't do, for all sorts of reasons, is share these tests with the world, in a public venue, so that others at, below or above their stature and experience could comment on, learn from, share, ridicule or improve upon. (this last bit was my maybe cryptic way of saying we should be lucky we're in a community where ideas and techniques are shared openly and not hoarded. I'm not saying "stop posting tests" and non-narrative videos)
edit: TLDR version -- y'all stop marginalizing folks posting test videos because that's how you familiarize yourself with your gear enough to be useful to yourself and anyone else. It's what the name brand pros do so snarky comments about yet-another-boring-test-video are really just ignorant.