I'd love to... Both of these are principles that describe how to make a TRX exercise more or less difficult.
Vector resistance applies to exercises that happen from a standing position.
As the feet move closer to the anchor point the body is in a deeper position and resistance increases. Alternatively as the feet are positioned further away from the anchor point and the body is in a more upright position and the resistance decreases. In this way any exercise can be adapted to suit any user or resistance can be easily adjusted during a set with a small change in foot position.
The pendulum principle impacts actions where the feet are suspended in the TRX. If untouched, the TRX simply hangs straight down from the anchor point due to gravity. We call this the neutral position. Any movement away from this neutral position will cause gravity to act in an attempt to pull it back to neutral. We can capitalize on this by changing our foot positioning in relation to the TRX.
If I position myself so that my feet are to the other side of neutral, when I suspend myself gravity will assist the action, swinging the TRX back toward the neutral position so in essence, gravity is assisting me with the movement. Alternatively if I position myself further ahead so that my feet are on my side of neutral, gravity will want to pull them back to neutral in the opposite direction that the movement is going in. This loads more resistance onto the exercise and is a great way to progress.
For a more visual description of Vector Resistance and the Pendulum Principle please click on the following video links
Vector Resistance http://link.brightcove.com/services/link/bcpid1463340999/bclid1420186430/bctid1420195923
Pendulum Principle http://link.brightcove.com/services/link/bcpid1463340999/bclid1420186430/bctid1420195914