Or with a single transistor:
Video Inverter near the bottom of the list.....
http://www.hobbyprojects.com/A/video.html
I built a crosshatcht generator using an EDN magazine "Design Idea" and tried the video out with a salvaged Astec modulator - no joy, so I rigged up a 2N2222A as an inverter, and voila....
BTW, it still works, and is more stable than my RCA portable unit...