It seems unlikely Khan Academy doesn't have the technical competency to deploy their video content to an alternate host rapidly, whether that be an object store (Backblaze) or dedicated servers with very cheap bandwidth (Hetzner, OVH, and similar), perhaps even using PeerTube.

There's a reason other non profits like Wikipedia and the Internet Archive run their own hardware, networking, and connectivity to transit providers. And before the "doing that is expensive!" argument comes up, note how expensive having someone else do these things are. Lots of margin built into cloud services.