Consume the nearby soldier to get his form then enter the base. Next, you have to consume the blackwatch trooper but be careful of the nearby detector as it can see through your disguise. After consuming the trooper, enter the briefing room for a scene.
Once in control, jump and press circle to pounce at one of the scientists and consume him. Chase the other three scientists to consume them as well.
Pounce and consume
After viewing the memory, you have to hunt for Dr. Shaffeld next. Once you've reached him, he will board an APC. Kill one of the soldiers carrying a rocket launcher then destroy the APC with it to complete the bonus objective. After destroying the APC, Dr. Shaffeld will escape. Chase him down and consume him to get his memory. Escape the alert to complete the mission.