Phorid has high HP and Defense. He lacks weakspots. He is not resistant to bullet or impact damage. This makes him suitable for testing.
Two Rifle Amps (http://warframe.wikia.com/wiki/Rifle_Amp) were used. These increase the damage of all primary weapons by the listed amount, in this case it is 54% (27%+27%).
The Sobek in the video is formatted for maximum damage-per-shot. It uses the same mods as the Hek in the previous video, which is also maximized for damage-per-shot.
Outside of the gun itself, no sentinels were damaging Phorid apart from perhaps 1-2 vaporize from a dethcube, which does negligible damage. Stomp was used to stun the boss for easy testing and it too does negligible damage to the boss.
No active buffs or debuffs (prime, roar, sonar etc) were used, besides the Rifle amps.
20 seconds kill time