Your logic or understanding is bad. The video is only requested after a rejection, not before submission. So Apple are not saving themselves time here, quite the opposite they are causing multiple rounds of review.

The app/game is already proven to work at the time it is compiled and again as it is uploaded and put through Apple’s first line of App Store checks.

Apple is already putting large demands on developers with enforced SDK changes and new devices, we need them to do more for us not less. Large companies might be able to eat the time required to do these videos, but as an indie developer it already takes hours or days to prepare the app store page. This is not good by any measure.

In that case they should be requesting the documentation first.