1. A method of providing measurement information comprising: receiving, at a census server, a plurality of hypertext transport protocol (HTTP) GET requests including a plurality of census events from a plurality of clients used by a plurality of users via a network, wherein each GET request includes a uniform resource locator (URL) containing embedded information for a census event that describes playback of a video provided by a hosting server to the plurality of clients, the census event comprising a content owner identifier identifying the owner of the video, a video identifier identifying the video, a playback identifier identifying a playback instance of the video, a channel name identifying a channel with which the video is associated, an internet protocol (IP) address of a client, and a client cookie stored by the client on behalf of the hosting server, and the census server and hosting server operated by a same entity; filtering out information that identifies an identity of the plurality of users and information that identifies a location of the plurality of users from the plurality of census events to produce measurement reports describing the playback of the video, the filtering comprising: filtering out the video identifier from the measurement reports; hashing the client cookie included in the census event to produce a hashed client cookie; including the hashed client cookie in a measurement report; tracking how many IP addresses within a specified address range are included in the plurality of census events received from the plurality of clients within a specified time period; determining whether at least a threshold number of IP addresses within the specified address range are included in the plurality of census events received within the specified time period; adding the specified address range to a whitelist responsive at least in part to determining that at least the threshold number of IP addresses within the specified address range are included in the plurality of census events received within the specified time period; and including a portion of each of the IP addresses included in the census event in the measurement report responsive at least in part to determining that an IP address in the census event is within the address range added to the whitelist; and including the content owner identifier, the channel name, and the playback identifier from each of the plurality of census events in the measurement reports; customizing information in the measurement reports to include additional details, wherein the customizing comprises modifying the content owner identifier to account for one or more attributes of the content; and providing the measurement reports to a measurement agency not affiliated with the entity operating the hosting server and the census server via the network using a persistent hypertext transport protocol (HTTP) connection in which a transmission control protocol (TCP) connection with the measurement agency is kept open for a subsequent report.