Despite this being a great video which entertained me quite a lot, you made quite some misconceptions, it is in fact possible (of cause) to use all 10 fingers for typing , a skilled typist could reach up to 100 WPM, sometimes even more.
A popular video of speed typing is showed here:
Also, IBM didn't introduced the single-printing element with their Selectric typewriter(s), in fact, typewriters with single-printing-elements such as type-wheels or cylinders, where intruded to the marked MUCH earlier, the Blickensderfer typewriter for example, which was a fully mechanical typewriter which used a interchangeable type-cylinder, was introduced 1893. Blickensderfer also invented the world's first electric typewriter, the "Blickensderfer electric", which also used the characteristic type-cylinder.
Aaaaaand Remington also didn't came up with the Type-bar system. QWERTY was also not specifically designed for Remington typewriters, but for Type-bar typewriters in general.