Update to simplified example (external video codec)

[neil-rti]

Simplified example that uses external video codec (defaults to FFMPEG/FFPLAY, but could use any codec that uses byte streams)

Benefit is better portability, and removes the brittleness of GStreamer, which was a headache.

Drawback is high latency of FFMPEG/FFPLAY -- appears to be around 2 seconds when running camera-->ffmpeg-->ffplay-->display (without Connext in the data path. Connext adds negligible latency).