- peering connection, or
- some sort of GGC-like nodes [Google Maps, YouTube videos]
Strangely, while www.youtube.com resolves to a locally-hosted server (18.104.22.168 currently), youtube.com (with no leading www.) resolves to a 208.65.153.xxx address, seemingly in Richmond, VA.
The caching nodes [presumably GGC nodes] currently serve only certain services (map tiles, YouTube videos) and are generally co-located within a client network. The other Google services are served from machines located in Cape Town (based on ping times) and that are administratively within a Google-owned IP block.
Assume this is a "small" trial run (limited number of users on TENET, maximum goodwill from helping the poor academics) before a full roll-out. The caching nodes already save TENET up to 45 Mbps international transport! There is no local visibility to Google's ZA IP block from IS's route server.