Video is nothing more than a series of still images played back at high speed, which can vary depending on factors like the standard in use and the refresh rate. Televisions, whether old CRT models or modern ones, generally apply the same tricks to convey a sense of uniformity to the viewer, and the best way to reveal those tricks is with a high-speed camera. That's where the Slo Mo Guys come in...
A common effect when filming a CRT television or monitor with a digital camera is that we can observe the 'sweep', caused by the lack of synchronization between the camera's shutter speed and the television's refresh rate, which also changes depending on other factors (resolution being one of them).
The creation of each frame is carried out line by line, from top to bottom and from left to right... but usually we can only see the vertical action (under the right conditions), while the persistence of vision does the rest. However, when we add a high-speed camera to the equation, the entire visual mechanism of a television is exposed:
How a CRT television works
In other words, the Slo Mo Guys took one of their fabulous cameras, filmed an old CRT television during a game of Super Mario Bros., and then repeated the process on a giant 4K television displaying the Xbox One logo when turning on the console. The most important difference is that with a CRT, brightness is limited to the active pixel line, but on a panel it extends to the entire frame.
Leaving aside slow motion, equally impressive is the creation of color. The camera allows us to understand the work of an individual pixel turning red, blue, and green on and off according to the color to be generated, and something similar happens with the phosphor dots of a CRT.
At the same time, observing individual pixels reveals the limitations of some televisions in reproducing the color black. No matter how much the pixel is 'off', its illumination does not disappear, and the result is an 'almost black' instead of a real black.
In contrast, OLED televisions (like the LG unit they received to make the video) apply individual brightness control on each pixel, thus delivering superior reproduction of the color black.
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