https://www.youtube.com/watch?v=IiQKD-kMAhc

Do you know that all it requires to shoot a 4k video is an 8.3Mp camera sensor?
Do You know that Smartphone Cameras with Higher Megapixels count use Binning Technology to reduce all images shot on Auto mode?
In Auto mode, a 108Mp camera stores images at 12Mp while 64mp stores at 16Mp and 48MP stores at 12Mp.

Nevertheless, there is one situation where the megapixels truly count.
Thanks to Gcam port developer Wyroczen, we tested it out and got a 62Mb size image from an Android phone of 64mp camera.

8.3MP isn't really enough for 4K video. I'd say the lowest should be 10MP.

Why? Because there has to be enough headroom for high dynamic range, higher frame rate and; of course, video stabilization. Else, what you'll get is soft footage that has been upscaled. Or, even worse; an oversharpened, aliased, artefacted mess.

thepoweruser:
8.3MP isn't really enough for 4K video. I'd say the lowest should be 10MP.

Why? Because there has to be enough headroom for high dynamic range, higher frame rate and; of course, video stabilization. Else, what you'll get is soft footage that has been upscaled. Or, even worse; an oversharpened, aliased, artefacted mess.

4k or Ultra HD resolution is 3840 x 2160 pixels
Multiply the two and it give you 8.29 million pixels ~ 8.3 MP.

Also note that most 8Mp camera sensors are about 8.6Mp