The following diagram illustrates something interesting: just as we can place a backend service (for example, a group of VMs) behind a load balancer for dynamic content, we can also place backend buckets behind a load balancer. It would also make sense to use Google's Content Delivery Network (CDN) to cache the content in those buckets in front of the load balancer, but that is not actually shown in this diagram:

GCP also features content-based load balancing, where an HTTP(S) load balancer can be set up to distribute traffic to different backends depending on the URL path. For instance, if the video content for your website is stored in a bucket, you could configure your load balancer to direct all requests to URL paths that begin with /video to your bucket. All other requests can be served by your VM instances: