Gemini 6, which was originally scheduled for launch in October, was planned to last 46 hours and complete some 29 orbits as well as perform four dockings with an Agena Target vehicle, to be launched just ahead of the Gemini 6 spacecraft. The original mission also had plans to carry live television coverage of the recovery, once it had completed its orbits. The aircraft carrier Wasp was outfitted with transmission equipment to beam TV coverage to the Early Bird satellite, which would have been the first such attempt at live broadcasting via satellite.
But a catastrophic failure during the launch of the Agena Target vehicle forced the scrubbing of the mission of Gemini 6 until it was reconsidered and decided to relaunch Gemini 6 after the launch of Gemini 7 in December.
All was going according to plan, right up to ignition. But after a little over a second, the engines abruptly shut down and forced the launch to promptly abort. At the time, no one knew why the mission suddenly quit, but it was one more disappointing turn of events for a mission having a hard time getting started.
This broadcast, via CBS News and the venerable Walter Cronkite from December 12, 1965, picks up shortly after the engines quit, and eventually goes over to Houston where a news conference takes place, explaining the situation from earlier in the day. It was determined the aborted mission was only a precaution and that launch would resume on December 15, much to relief of the Gemini 7 crew, James Lovell and Frank Borman.
Here is a one-hour excerpt from that broadcast as it was first heard and seen on December 12, 1965.