さえ (sae) and すら (sura) - what do they really do? How to use them. What's the difference?

Picked one by one from a mixed channel; title passed two strict editor passes and the clickbait rules.

A 9-minute video from Organic Japanese with Cure Dolly: “さえ (sae) and すら (sura) - what do they really do? How to use them. What's the difference?”.

Video by Organic Japanese with Cure Dolly, played through YouTube's embedded player.