Meta owns their data centers, so I don't think that framing is quite right. Increased traffic might cost marginally more in terms of electricity usage, but I think mostly what would happen is the service would degrade.
The hardware serving web requests on Facebook is very different from the hardware used to generate these videos. It’s different kit, that is currently quite expensive and power intensive.
Facebook absolutely does not have a fleet of GPUs idling that could suddenly spring into action to generate a billion of these videos, nor do they have power stations on standby ready to handle the electricity load.
Right, my point is that "paying a million dollars instantaneously" isn't something that Meta would face the way a company with a public cloud infra would, and as a result their motivations / concerns are probably more along the lines of bad user experiences (due to performance bottlenecks) hurting public perception rather than runaway costs bankrupting the company.
Having recently seen cost analysis for hosted enterprise generative AI, we’ll continue to disagree on this point. You certainly are describing valid concerns but Meta never struck me as being particularly worried about how people think of them; and, I am certain this doesn’t have the ’degrade’ capability at the billion users scale — it would have work queue lengths measured in weeks or more, which is useless for social media.