YouTube had peering agreements in place even before the acquisition. And the instant the contract was signed, Google's fiber wasn't near YT's (then) five-six lo

YouTube had peering agreements in place even before the acquisition. And the instant the contract was signed, Google's fiber wasn't near YT's (then) five-six locations, so it was of little use. Actually, in November 2006 YT had a lot more (frontend) egress bandwidth than Google, whose dark fiber was mostly for its internal backbone. It took a couple of years before there was an unified CDN, at which point YT had already grown many times over.