not when u hide behind a corner in a little room. like in your vid u posted. granted u were on SWAT. but same tactic applies.
hide in a room. shot gun 1 shot is faster then 5 DMR shots. and sadly thats what the game turned into. get the lead, hide with shotgun and wait for someone to turn the corner. which really sucked cause i LOVED doubles and was looking forward to 50. but said fluff it when they took all verity out of the game.