In all fairness, the theatrical cut of Battlestar Galactica was meant to play in theaters outside the U.S., before the show aired on ABC. (Had the internet been around back then, we would have had plot spoilers from Canada!) It has many key differences from the tv version. Baltar gets beheaded for example.

The series was probably the most expensive tv show ever at the time, and Universal wasn't about to pass up a chance to make some box office dollars in the wake of Star Wars mania.

The movie version was also was presented in Sensurround, which was how bass freaks got their fix in the 1970's. ;)

Walt Disney had tv and theatrical versions of many shows in the 1950's. The movies made money overseas, and aired as several chapters on his tv show here. So this concept is really nothing new.