Rosencrans enlisted and served in the United States Army Air Forces, then earned bachelor's and master's degrees in economics from Columbia University in 1949.

Rosencrans conceived the idea of a cable system after BOT purchased TelePrompTer in 1956 with the goal of expanding its closed-circuit programming.

The company did so in order to broadcast "Thrilla in Manila", the third and final boxing match between Muhammad Ali and Joe Frazier, to its subscribers in Florida.

[1] Rosencrans offered Robert L. Johnson air time on Friday evenings, which led to the creation of BET, a basic cable and satellite television channel targeting African American audiences.

[1] He was an early financial backer and founding board chair of C-SPAN, an American public affairs television network.

[12] In addition to his work in cable television, Rosencrans was an early investor in PublicAffairs, a publishing company established in 1997 by Peter Osnos.