Underworld: Evolution (2006)
Reportedly, this part was cut right after rest of the scene was heavily edited because of Beckinsale's demands not to include any shot that would show her completely nude. The scene was filmed with both her and Scott Speedman being fully nude which is why it required some big cuts during later editing of the film. This also explains use of fade outs in between the shots of the scene and some bad edits of it. However, because of these reasons later part of the scene where Selene is on top of Michael and they continue to have sex until she has another orgasm couldn't be re-edited to look properly which is why it hit the cutting room floor.
But if the later scene where Marcus stabs Selene and starts drinking her blood and seeing her memories is slowed down (this scene takes place about an hour into the film), one or two single frame shots can be seen which show bit more nudity from Selene and her starting to get on top of Michael. These shots were part of original sex scene and were accidentally left in during editing of the film.
Director Len Wiseman said in the commentary for the theatrical cut of the film recorded in 2006 how there were some scenes that were deleted from the film and how there might be an extended version of the film released sometime after the DVD release, just like the first film had, but that never happened. He also mentioned in some interviews when the movie was released in theaters how the original cut almost got an NC-17 rating, mostly due to the level of violence and gore but it was also hinted that one of the other reasons why the original version of the sex scene between Michael and Selene was cut down is because that scene alone would probably earn the movie an NC-17 rating.