Considering this was seemingly a mostly North America-affecting networking issue, and the 10% reduction in views was global, it doesn't sound like YouTube got much of a priority - quite a lot of the videos that were actually view-able in affected regions during the outage may simply have been served from edge caches.
Disclaimer: no inside knowledge, the above is pure supposition
You're right, but I wanted to point out their poor wording. They shouldn't downplay the huge impact on GCP customers in one paragraph, and then gloat about YouTube being fine in the next.
It's undermines their GCP business in a big way too - It makes you think that if they had to choose, they would throw their GCP customers under the bus to preserve their own other services. The value proposition of GCP is greatly diminished then in comparison to a dedicated cloud provider like DigitalOcean, who has no other competing interests. This changed the way I view some of these cloud providers.
eg. If Google had to prioritize ad network traffic over GCP, there's no question the ad network would get priority. But why not just go with a different provider who doesn't have to make that compromise?
Disclaimer: no inside knowledge, the above is pure supposition