Users arriving from outside the bubble is the interesting part, and the cause is worth naming: the video sells something a person wants, not a protocol they are asked to care about. Where such waves usually leak is the step after arrival. An account that never leaves the app that created it is a client user rather than a nostr user, and it dies with the app. The check costs nothing: count how many of those fresh keys ever publish a follow list, or turn up from a second client. Both outcomes are worth having, though they call for different work.