This download includes a small video and a 4k image taken from Big Buck Bunny
The video is 360 x 360 pixels and has 1024 frames.
The image is a single frame extracted from the 4k video so it's 3,840 x 2,160 pixels
These purpose of these files is to allow you to fairly compare any timings we quote and get a rough estimate of how long something will take on your machine.
If we say something takes 20 minutes (the video) and it takes 10 minutes on your computer then when we say something else takes four minutes you can easily work out that on your machine the same thing will take two minutes.