The original
Battlestar Galactica aired my senior year of high school (1978-1979) and it is still my all-time favorite TV series. I've seen a number of variations of each of the episodes, which is I think why you've gotten several answers to your question.
"Saga of a Star World" I've seen at least six versions of it: (1) The Sept. 17, 1978, pilot episode, which was 2 hours and 40 minutes long, in a three-hour time slot; (2) The theatrical version, which was released in Canada and Europe in summer 1978, before it premiered on US television, and in American theaters in May 1979, which is 2 hours and 20 minutes long and is missing several scenes, including the one in which Starbuck proposes to Athena, but has an added scene at the end where Baltar is beheaded; (3) a shortened TV version, also 2 hours and 20 minutes long, which includes scenes not included in the theatrical version such as Starbuck proposing to Athena, but deletes other ones; (4) a TV movie version for a two-hour time slot which deletes ALL those scenes; (5) if you've got the DVD set you will see extra scenes never included in any of the above, because Glen Larson had originally conceived of a "Saga" as four-hour miniseries; and (6) when the show airs in reruns over three nights on TV, some tiny segments are eliminated each night to make room for more commercials (TMRFMC).
"Lost Planet of the Gods" (LPOTG) There are three versions: (1) What originally aired in 1978 over two nights; (2) What is shown in two parts in nightly TV reruns minus some scenes TMRFMC; (3) a two-hour syndicated TV movie from 1981 with additional scenes that you can now find in the extras on the DVD set.
"The Lost Warrior" (LW), "The Long Patrol" (LP) and "The Young Lords" (YL) See comments 1 and 2 regarding LPOTG, plus additional comments below
"The Gun on Ice Planet Zero" See comments 1, 2 and 3 for LPOTG
"The Magnificent Warriors: Same as LW et al
"The Living Legend" (LL) See comments for 1, 2 and 3 for LPOTG. A theatrical version of this episode was released in Europe, featuring most of the scenes from LL, plus additional scenes from FIS (see below)
"Fire in Space" (FIS) Same as LW et al
"War of the Gods" (WOTG) See comments for 1, 2 and 3 for LPOTG
"The Man with Nine Lives" (MWNL) and "Murder on the Rising Star" (MOTRS) Same as LW
"Greetings from Earth" (GME) This episode originally aired in a two-hour time slot in 1979. That version also aired as a TV movie in 1981. When it is shown over two nights in syndication, a number of scenes are deleted TMRFMC.
"Baltar's Escape" (BE), "Experiment in Terra" (EIT), "Mutiny on the Celestra" (MOTC) and "The Hand of God" (HOG) Same as LW
So what did Universal Studios do with the single episodes? They were cobbled together in 1981 to make a series of semi-coherent TV movies, and to create continuity, additional dialogue was dubbed in by unknown, unseen actors in a number of scenes (the voices don't match). The combos were: Lost Warrior/Hand of God, Man with Nine Lives/Baltar's Escape, The Long Patrol/Mutiny on the Celestra, Murder on the Rising Star/Young Lords; and Experiment in Terra was combined with the final episode of the series
Galactica 1980 (another story altogether), The Return of Starbuck (ROS), with bizarre added footage at the beginning and the complete elimination of Angela.
As for video, you could find the following before the entire series was finally released together on DVD:
1. The theatrical version of the pilot was available on VHS, DVD, LaserDisc and I think Betamax
2. The European theatrical version of LL on VHS
3. The two-episode TV versions of LPOTG and GOIPZ were released on VHS (not the TV movies), as were LW, LP, YL, MW, FIS, MWNL, MOTRS and BE, and also ROS.
To confuse you even more, a number of episodes, both one- and two-hour, were written as novelizations, and they don't follow the plots of the episodes, with elimination of some characters and additions of new ones.
Got all that?
Oh, and the comments about Richard Hatch are from me:
They're highly fond of the famous