Speaking to MTV, Cameron described the lovemaking scene between Sam Worthington and Zoe Saldana as "alien foreplay", noting that it lasts "all of about 20 seconds".

Cameron said: "It's been restored, every last frame of it. Seriously. I would say, just so that we correctly manage people's expectations, it does not change our rating at all. I would call it more of an alien foreplay scene. It's not like they're ripping their clothes off and going at it."
In a separate interview with Movieline, Cameron explained that he removed the scene for the initial theatrical run after getting a negative reaction from test audiences.
"I always felt that it was a good moment, so I wanted to put it back in," he said. "I mean, what have I got to lose? The film's already a big hit. I think it’s actually an illumination of the Na'vi way: There’s a Na’vi way for everything, including making love.
"Of course, I just want to be clear for the record that it's only an additional 20 seconds. The 'horizontal bop' part of it still takes place off camera after the dissolve."
source: DigitalSpy
Cameron said: "It's been restored, every last frame of it. Seriously. I would say, just so that we correctly manage people's expectations, it does not change our rating at all. I would call it more of an alien foreplay scene. It's not like they're ripping their clothes off and going at it."
In a separate interview with Movieline, Cameron explained that he removed the scene for the initial theatrical run after getting a negative reaction from test audiences.
"I always felt that it was a good moment, so I wanted to put it back in," he said. "I mean, what have I got to lose? The film's already a big hit. I think it’s actually an illumination of the Na'vi way: There’s a Na’vi way for everything, including making love.
"Of course, I just want to be clear for the record that it's only an additional 20 seconds. The 'horizontal bop' part of it still takes place off camera after the dissolve."
source: DigitalSpy