I'd call it an endurance video for lower body, but you can use it for strength for upper body. For the lower body, there are fairly high numbers of repetitions without breaks in between. It's hard to go heavy because you move right from one thing to the next. (For example: 16 leg presses followed by a long set of squats followed by 16 more leg presses on the same side followed by a set of side lunges on the same side.)
For the upper body, there are far fewer reps for each part, so it's easier to go heavy.
By the way, I love this video. It's not the traditional Firm style at all, but it keeps moving.