When Kensi puts the camera on the wall in the garage she attached it to the wall at about shoulder high which is approximately 5' to 5'-6" off the floor. When they bring the camera up in ops the angle is above the open hood of the car immediately in front of the camera and the angle is about 9' to 10' above the floor. Also there is a 6" drain stand pipe in front of the camera but it is nowhere in the camera view.
Gibbs has had an 18-year grudge against Mace because she investigated him for the murder of the man responsible for murdering his wife and daughter. But Gibbs has walked free for 18 years despite being guilty, so either Mace failed to find evidence, or found evidence and buried it. (Turns out, it was the latter.) Either way, he got away with it. Zero reason for a grudge against Mace.