In Final Cut, this effect can be achieved via "Strobe" –which, as you say, lengthens the duration of some frames and eliminates others, but otherwise leaves the moment intact, neither slowing the film down or speeding it up.
The original "Chungking Express" style effect was created by shooting at a lower frame rate. Doyle and Wong Kar-Wai claim they did this because they were dealing with a low light situation (it is a practical solution) but they obviously maximized its aesthetic potential. Forgive me for not knowing the film terms. I've shot exclusively in video so far.
