This is a valid point but it highly depends on the use case and larger context on whether this will be relevant or not. If you have a table where you fetch multiple rows close to each other in paginated manner this would be relevant for the performance but if you only fetch individual records by uuid, data locality wouldn’t increase the performance.
Yes we understand that - but these were her options: continue hosting on YouTube, host on another site/hosting service (a lot of new anti-YouTubes are popping up), or self-host. She had a choice in this. YouTube being the most popular of them all doesn't mean she has to host her videos there.