Note that what we see here on this 20th Anniversary DVD release is the full "Extended Version" or Director's Cut of the film. Apparently, the original US theatrical release in 1984, or at least the original pan and scan US videocassette release of the next year, was an edited version, cutting some 6 minutes out of the film. These cuts were made for timing/pacing reasons only, not for censorship of violence or sexual content. The "Extended Version", with the 6 minutes reinstated, was originally released in 1992 and is the version of the film seen in all subsequent video cassette reissues, the laser disc release and the new DVD release.
For those interested, the 6 minutes of reinstated footage revolves predominantly around two areas. Firstly, the film's introduction, with the overture and early scenes, showing the apes in Equatorial West Africa, reinserted. The expanded scene serves two purposes; it acts to bookend the film, along with the film's final shot in the jungle, and 2/ from a plot perspective, it sets up the accidental death of an infant ape, as caused by the rough treatment of its tribe leader Silverbeard, thereby providing some back-story to the later antagonism and ultimate showdown between Silverbeard and Tarzan. Secondly, some sequences involving D'Arnot and Tarzan's stay at Buller's inn (the "edge of the world", en route to civilisation) have been reinserted, to show more of John's education by D'Arnot, specifically his teaching of fire, and later its payback as John uses fire to rescue D'Arnott from the roughneck crowd and help them both escape. Again, the reinstatement of these sequences is a welcome inclusion to provide more clearer context to John's education and his slow transition to civilisation.