Kirby_Pwns_All, The red laser is most likely from a sniper riffle or any long range weapon(You can see the people where the laser comes from in both sections). My bet it's the strike rifle's second feature or just some kind of new weapon.
Wait, it looks like you throw some type of round to the opposition when you tag them with the laser of doom. It seems to look like the grenade ammo you put inside the tube or grenade launchers in other shooters.
Well thanks for the incite on that. Though I'd like to know, in the carbonizor/er section of the video, after tagging the enemy doesn't a granade type of explosive launch out towards the enemy that's tagged?