Here is a video I made of Tri-Rail trains at the Tri-Rail/Metrorail Transfer station. I've also threw in two bonus clips, one at the beginning and one at the end. I've stayed for the beginning half of the afternoon rush hour.
Trains:
Cypress Creek
Train 1: Tri-Rail P685
Tri-Rail/Metrorail Transfer
Train 2: Tri-Rail P682
Train 3: Tri-Rail P627
Train 4: Tri-Rail P632 (deadhead)
Train 5: Tri-Rail P632
Train 6: CSX L789