I think SeekSound belongs to the Sound-Library like SeekMovie (which is already implemented) belongs to the Movie-Library.
Please don't say "So use the Movie-Library", as this doesn't work for me because the movie library is not too accourate with playmovie. For instance, try Playsound ten times with the same sound, you hear a LOUD single sound, try Playmusic ten times with the same sound, you hear a crowd of sounds playing weird and confused...
Last but not least the SeekMovie doesn't work correctly with Sounds.