Equipment used includes a 4-6" step, stability ball, medicine ball, and two sets of weights. You definitely need the stability ball (Core Secrets fans will recognize many of the exercises using the ball). I think the step is optional. It is only used in two tunes, and on the first tune the routine moved so fast I felt more secure doing it on the floor anyway. For the second tune using the step you stand at one end and alternate squatting off each side; you could do this move on the floor, or use the High Step Topper or the top section of the Fanny Lifter.
For the medicine ball I used my old two-pound Firm Ooof ball. On most of the medicine ball sections you can use one light dumbbell held at each end, but there is one tune where the ball is passed rapidly from hand to hand, so if you don't have a medicine ball you should probably choose a play ball or pillow for this part. For weights you need two sets of dumbbells: one 3-lb. set and a heavier set (I confess I was plenty challenged using a 5-lb. set for my "heavier" weights).
Bonnie Geer leads the workout. There are three background exercisers. Although Bonnie occasionally mentions "beginner" moves, no one in the cast really does them (as opposed to CF, where one exerciser often performed a less intense variation of an exercise). The pace is quite quick, including the equipment changes.
FS is different from most strength videos I've seen. The best comparison I can offer is to Core Secrets Accelerated Training Camp (which has some similar moves, but is much less intense and lacks aerobic tunes). The moves in FS are designed to challenge/improve core stability, which in turn facilitates the functional moves used in everyday life. The exercises are usually compound(such as a dip while raising one dumbbell overhead), and are often done with a balance element (like standing on one leg) or with a larger range of motion than usually seen in classic weightlifting exercises.