The ETag header serves as a unique identifier for a given resource version. If a file changes, so does the ETag header, providing a mechanism to improve caching.
As long as the Optimize for Video Delivery option is disabled and an ETag header is present on the origin response, we will passthrough the header and cache it accordingly. If the resource is compressed on our end (gzip, brotli), the ETag will be marked as "weak" by prepending a W/ in front of the ETag string.