Not really, because users with a high page load time can skew the average by a very large amount.
Hypothetically, let's say that previously they had 10 users who all took 2.5 seconds to load the page, so their average page load time is 2.5 seconds. After the change, those users all drop to a 1 second page load time. They also attracted one new user who now only has to wait 20 seconds instead of 50 seconds. Their average page load time is now 2.7 seconds but their usage only increased by 10%.
Youtube use would have to be > 2.5 times as big after for the resource usage to have actually grown.
Not Jevons paradox's, not sure what to call it.