Some of those extras in the background that you mentioned may actually be people who did the upgraded FX works for the remastered DVD Sets; they actually worked themselves into some of the scenes where they felt they could.
And the reason you get the military feel that you also mentioned was because Roddenberry and others behind TOS had actually served, so it's present and noticeable in that show, whereas the shows that came later were worked on by pantywastes who were never in any branch of military service, and their writing reflected that fact also.
Just out of curiosity, how much did you get the Set for?
>>Possible, but I don't think so. These are people moving around, doing things in the background, and occasionally you see Kirk or somebody reacting to one of them.<<
They move around also in the scenes I alluded to. I recall one scene where it was pretty darn noticeable because the guy was behind the transporter console wearing an outfit that didn't seem consistent with the ships crew I seem to recall. It looked like something out of TNG instead.
You didn't tell me how much you paid for it. I bought all three at a reasonable price last year. Best Buy had a great deal on all three, so I went for it.
I forget which season and episode the scene I mentioned appeared in --it may not have been Season 1. In fact, I think it was one of the later seasons actually, where they may have felt it all right to get a little bolder in terms of what they wanted to do.
As for what I paid --I got all three Seasons of the re-mastered episodes for $99 at Best Buy when they were running a special sale. People had to go to their website repeatedly the week they were running it though as I recall in order to get them for that price.