I believe this is the original song (Catonese version) to the movie Swordsman II (starring Jet Li, Bridgette Lin, Michelle Reis, Rosamund Kwan, and many others). Why? Simply because Rosamund's lips are actually in sync with the lyrics! Well, not in this video since the audio's out of sync.
If you've seen other clips of this song part, you'll noticed that there is no male singer at the beginning of the song and that when the female sings, she sings in a different dialect or with lyrics. Hence, why Rosamund's lips aren't in sync with the lyrics in those song clips. Don't get me wrong. I like that version of the song, too, but I was getting frustrated when I couldn't find the original version, so I decided to upload it myself. I don't know the title of the song, but I've always called it "The Sea Laughs". Others had called it, or other versions of it, "Cang Hai Yi Sheng Xiao."
No copyright infringement intended. I do not own the song nor the clip.