Back in 1999 I heard about the U.S. cable television network Sci-Fi Channel scheduling 'special editions' of the original Star Trek series: Each episode would be shown uncut with additional behind-the-scenes material shown before and after and during commercial breaks. In the mid to late 1960s, the years of Trek's production, running times for completed "one hour" shows was about 51 minutes (allowing for commercials). As the years moved along hour long series episodes became shorter and shorter in order to make room for even more commercials. What happened to older programs which were being re-run in the new broadcast model is they had to be trimmed by a few minutes -- "time compression" is another lovely device that's a system of speeding up the picture and sound by a small percentage (while correcting for audio pitch) to help in the ultimate aim of fitting an episode into tighter and tighter slots.
The best way to allow for the whole bag of episode to run complete and at normal frame-rate is to schedule the beast in an over-length time slot. Because the network or station is now stuck with an odd length, the best thing to do is to pad out the slot with something else. In the case of the Star Trek special editions this was done by producing a eight-minute, or so, behind-the-scenes video. Interviews included actors, writers, and production crew.
Star Trek's first pilot episode "The Cage" has long been one of my favourite Trek's, considering the fact that with the exception of Mr. Spock there is no one from the regular series in the ship's crew; there is Jeffrey Hunter, but he is very much a different leading man than William Shatner. It would be hard to imagine Hunter carrying an episode such as "The Omega Glory" ("They must apply to everyone, or they mean nothing! Do you under-stand?!").
Pilot episodes are used primarily to test the proposed show. Actors can be replaced, characters changed, fine-tunings of various kinds undertaken before regular series production; but the idea is front-and-center. Although they turned-down Star Trek, based on "The Cage", NBC liked the concept and was impressed with the technical elements and 'physicality' of what had been accomplished, so they commissioned an almost unheard of second pilot. (Sitcoms have a history of second pilots being produced, but they are relatively cheap to restage.)
Principle photography on "The Cage" took place over three weeks in November and December of 1964 on Desilu's "Culver City" stages 14, 15, and 16.
The pilot was designed by Pato Guzman, Franz Bachelin, and Walter "Matt" Jefferies (who's main baby was the Enterprise bridge set, and an absolutely fabulous set it was, in all its electrics). The efforts of these talented gentlemen established the look of Star Trek which resonates to this day.
Composer Alexander Courage wrote the stand-out melodious and percussive score. He was chosen to score the pilot after much discussion; not only was he a highly regarded arranger (as in the MGM musicals), but he had an encyclopedic knowledge of music: all things which would benefit a space-travel series.
One word of warning about the video: Majel Barrett says that NBC, or the test audiences for "The Cage", did not like Number One, which is why the character never survived past the pilot. That is false; that was Roddenberry's excuse for years. The network felt that it had been railroaded by Roddenberry (Barrett was his girlfriend at the time) in casting her in the role instead of casting the proper way. NBC demanded more control and influence in production of the second pilot, "Where No Man Has Gone Before". The joke is, like a lot of fans, I like Majel Barrett as Number One.
The Cage Star Trek The Sci-Fi Channel Special Edition Extras