I have discovered not so long time ago that
RF mixers can be used as switches. I am using
one of the MiniCircuits RF mixers (see
http://www.minicircuits.com/) controlled from the
PC parallel port to swith between five sensors which
output 5 to 35 MHz signals (should be well within
the badwidth of CCTV). The simple trick is to
connect all mixer outputs to the common output,
inputs to each LO and the current source (in my
case the parallel port, in your case the uC) to
the REF oscillator input.

See one of the application notes/FAQ on the
MiniCircuits web site for more details.

Jean-Michel