Audio problem: In the beginning, when Murtaugh's daughter comes downstairs in the black dress the dialog is dubbed in. After the spin, she's talking but she doesn't move her mouth (even before the spin she isn't in sync). Her little sister replies and doesn't move her mouth either.
Audio problem: Right after Riggs handcuffs the suicidal man, the next shot shows Murtaugh saying "oh no" but his lips don't move.
Answer: The jumper's name was Len McCleary. He was played by Michael Shaner and is credited for the role in the film (and on IMDB).
Bishop73