There have been a number of small complaints about the damage dealing potential of the Monk class in Diablo III, which has been criticized by existing beta testers (according to those on closed forums) as being somewhat lacking compared to the Monk's counterparts.
A new video from the beta might put those complaints to rest, as it shows the Monk dealing enough damage to accumulate up to 1200 experience points—a number that's supposedly big for the character's level. The player character earns a variety of "Mighty Blow" achievements for slaughtering upwards of six enemies within a single strike, and eventually earning the "Massacre" achievement for killing so many enemies in a row.
The overwhelmingly large event is an example of a rare event within the crypts.