This version runs at 424-minutes, that's 7 1/2 hours in length, and cuts the first two films chronologically (because Part III is the suck) while also adding footage that was left out of the theatrical release. However, don't think this is the first time this has happened. NBC aired an edited, censored version back in 1977, and then released later as part of an uncensored VHS boxset. Still, this has to be a treat for fans of The Godfather to be able to see the film in a fresh way after all of these years.
The next airing of The Godfather Epic will be on January 23rd, but you can watch it now on HBO Go.