a1k0n : projects : colecovision A/V output modification : video amplifier schematic
C2 is a power supply bypass capacitor. It may not be necessary, and then again it may make a world of difference if you have a snowy output. Use something like 1µF or higher.

The LM318 is set up as a voltage follower as recommended by its datasheet. It feeds into C3, which removes the DC component of the video signal, and R3/R4 provide a 75Ω impedance match.

I tried some single-transistor emitter follower designs, but the impedance is too high; it drags down the RF circuit's weak signal. The LM318's relatively high input impedance seems to work out rather well.

Also, the 150Ω resistors in parallel can just be one 75Ω resistor... I just didn't have any extra 75Ωs in my resistor drawer.