those that leap on the threshold - the servants of the princes, who, after having gotten prey (like hounds) for their masters, leap exultingly on their masters’ thresholds; or, on the thresholds of the houses which they break into [Calvin]. Jerome explains it of those who walk up the steps into the sanctuary with haughtiness. Rosenmuller translates, “Leap over the threshold”; namely, in imitation of the Philistine custom of not treading on the threshold, which arose from the head and hands of Dragon being broken off on the threshold before the ark (1Sa 5:5). Compare Isa 2:6, “thy people ... are soothsayers like the Philistines.” Calvin’s view agrees best with the latter clause of the verse.
fill ... masters’ houses with violence, etc. - that is, with goods obtained with violence, etc.