200gig was surpassed what, 8 years ago? They have super active load balancing based on your region. You could purchase a Fiber gigabit line and only watch videos 24/7/365 and nobody at YouTube would ever notice.

As I said it's 100 times more advanced than that.

They can switch IPs, datacenters, regions, whatever they want. They even have access to BGP routing.

They also use some custom switches according to Wikipedia:

The private side of the network is a secret, but a recent disclosure from Google[90] indicate that they use custom built high-radix switch-routers (with a capacity of 128 × 10 Gigabit Ethernet port) for the wide area network. Running no less than two routers per datacenter (for redundancy) we can conclude that the Google network scales in the terabit per second range (with two fully loaded routers the bi-sectional bandwidth amount to 1,280 Gbit/s).