It is possible to use the shutdown feature of all Texas Instruments high-speed amplifiers in order to be between two or more sources, video sources in this case. The reason this can be done is the shutdown state, the output is in the high impedance, or High-Z state, which means two outputs can be tied together and whichever one is on will determine the output voltage. Here is a list of high-speed Op Amps manufactured by Texas Instruments which allow this capability. A parameter which is specified in most devices specifically intended for video is the output glitch during turn on and off transients. You would want to check the data sheet and make sure the output glitch is acceptable in your system. Here in this table, they are tabulated on the right-hand side.