Methods, apparatuses, and systems for improving utilization of a communications system (e.g., a satellite communications system) are provided through techniques referred to herein as “deltacasting.” Some embodiments use a server-side optimizer to intercept and create fingerprints of byte-level content data traversing links of the communications system. The content fingerprints are used to transparently identify communications patterns (e.g., repetitious downloads of the same content, correlations between users, etc.), which may then be used in exploiting multicasting and/or other opportunities for increased utilization of the communication links.