as the most likely form of attack on the president, at present, would be a viechle-bomb or suicide-bomber with IED, i can see no real use for this admittedly awesome piece of kit. the mini-gun shown in that video fires around 2000 rounds per minute, and has no real means of sighting, meaning it is effectively an area suppression weapon - putting as much lead in the general direction of the enemy as possible..
now, given the Americans well-known indifference to 'friendly-fire' incidences, and the secret services unwillingness to cooperate with other federal agencies, let alone forign goverments etc - plus the well known guriella tactic of 'hide behind the civilian to inflict maximum casualties' - it seems a bit silly to me for them to be tooling up with such serious weaponry - from their own track record there just gonna end up slaughtering there own people, or worse ~ ours!.