Well, at least partially explained. More like assumed actually unless you can understand the Japanese that is being written in the video. Still, in the video below you can watch Patroklos learn how to use the Soul Calibur V Critical Edge system as he is taught by the director of the title, Daishi Odashima.
From what the video below shows, we are able to see that the Critical Edge system will be something similar to a special attack that can be used whenever the fighter deals enough damage to raise the meter that is next to their HP bar. Once the meter is filled the player can then use one Critical Edge attack which will deal a large amount of damage to an enemy through a spectacular attack unique to each character.