Why 2200 x 1800 pixels for video fallback image?

One INSPIRO tutorial suggests to make videos at 720p, which is 1280×720 px.
But two INSPIRO tutorial recommendations say:
Recommended Image size for Slideshow – 2200x1800px
Recommended size for Featured Image is: 2200x1800px
Those aspect ratios of 11:9 are different from the video aspect ratio of 16:9.
Shall I stretch (or what?) my first video frame to make such a first load/fallback image?

@GlennJohnsonScheper Hello,

For video we recommend a smaller size of 720p, as usually larger videos will take longer to load, but for web it’s not necessary to have your videos in the highest available quality, especially that they will play in background.

As for the image size, there was a mistake in the documentation.

The theme simply crops images in the Slideshow to the width of 2000px, while the height will be automatically cropped to the needed size to keep the same aspect ratio.

This means that if you upload a large image at the aspect ratio of 16:9, like 3600x2025px, then the theme will resize it to: 2000x1125px, which means that no portions of the image will be cropped.

Sorry for the this misunderstanding and confusion.