Bandwidth management and advertisement insertion in media content delivery systems and methods

An exemplary method includes a media content delivery system transmitting a transport stream containing an advertisement channel and a program channel, the program channel carrying a media program stream at a first bit rate, detecting an upcoming advertisement break within the media program stream, inserting, in response to the detecting of the upcoming advertisement break, an advertisement content stream having a second bit rate that is lower than the first bit rate into the program channel to temporally coincide with the advertisement break to free bandwidth in the transport stream during the advertisement break, and inserting an additional advertisement content stream in the advertisement channel, the additional advertisement content stream temporally coinciding with the advertisement break and utilizing at least a portion of the freed bandwidth in the transport stream. Corresponding methods and systems are also disclosed.