Assuming that this video is playing in real time, the shaking in Haiti lasted at least 17 seconds, possibly longer.That's a LONG time. Two critical things that affect building collapse during earthquakes is the time of shaking and the "period", that is, the frequency with which the ground moves back and forth, up and down, or a combination of both. Seventeen seconds is a LONG period of shaking. Again to put this in perspective, Loma Prieta 1989 shook for about 15 seconds; San Francisco 1906, for between 45 seconds and a full minute.
These poor bastards were utterly hosed.