I don't have the Lotte Berks but they are barre workouts. They go at a much slower pace than Squeeze or Physique 57 but are very good if you're first starting out because they are excellent at pointing out the proper form.
If you want something similar to the pace of Physique 57, you might want to try Cardio Barre 4 in 1 or Ultimate Advanced Cardio Barre. The 4 in 1 goes from beginner to advanced. The Ultimate Advanced is just what it says. It also has two bonus workouts - Power Arms & Power Thighs which are both brutal. Power Arms has lots of tricep work and Power Thighs mainly concentrates on the glutes and you will be begging for mercy.
Squeeze has a more athletic feel than most barre workouts. You also should check out, as others have said, Pure Barre. The original Pure Barre is also brutal on the thighs. Sometimes it's hard to see the angle that she's holding the leg or the foot since the production quality is somewhat poor and she's wearing black pants. Some believe it is the most advanced. Carrie Rezabak also came out with Pershing Square 1 and 2. I only have 2 which I believe is slightly more advanced from the reviews I've read. It also uses a ball. You could probably use the ball from P57. 2 has lots of work for the hamstrings. She is also coming out with a new series - I think it's called Lowry Loft which is due out soon.
Another favorite is Tracy Anderson. If you don't listen to her and just do the workout, it's great. People don't agree with lots of what she says but have gotten great results from her workouts. She's not the best at cueing but once you do them a few times, you get the hang of it. Her first offerings were the Mat Workout and Post-Pregnancy Workout. Her Mat Workout has larger range of motion movements than P57. It also has standing unweighted core work kind of similar to the movements in Core Rhythms. You don't need to have had a baby to do her Post-Pregnancy Workout. This one has about 22 minutes of core work which includes a bit of plank work. There is also a short, intense leg section mainly for the glutes and an unweighted arm section. I prefer the unweighted arm section from Mat as do most people. Tracy also came out recently with her Perfect Design Series which has 3 workouts. #3 is supposed to be the most advanced. Most people love these for the leg work but don't like the arm work on these so they usually do the leg work on these and the arm work from the Mat Workout. Tracy says to only use 3# on her arm work but that's probably all you'll be able to use for a little while because her weighted arm series really wipes you out. I have never used more than 3# yet because the weighted section comes after the unweighted section and your arms are usually fried by that point.
You should also look into the Exhale Core Fusion DVDs. I am currently doing a Core Fusion challenge this month (20 DVD workouts, classes or classes from yogavibes.com). The DVDs are divided into 10 minute segments. You can do the entire workout or mix and match with other workouts. The DVDs are: Thighs & Glutes, Arms & Abs (comes with a resistance band - there are 2 arm workouts and two ab workouts (one uses a band and one uses weights) and a stretch segment for upper back, back and hips; Lean & Toned, Pilates Plus and Body Sculpt. All are done in voiceover except for Lean & Toned which is like being in an actual class. Lean & Toned is the toughest IMO. There is a really tough Flat Back/Round Core segment which is done against a wall. I thought I had a strong core but this segment is really tough. There is also a Flat Back/Round Core segment on Pilates Plus which is not quite as tough. They are also coming out shortly with a Yoga and Boot Camp DVDs.
Then there are the Fluidity DVDs but to get the best workout, you would need to get the Fluidity barre. These include beginner/instructional, intermediate, advanced and seat and thigh. They also came out with Fludity Real Class 4 in 1 workouts. Many people say the music is really bad on these. I only have the intermediate and advanced which are between 35-42 minutes.
Lastly there is Callanetics. I have the Super Callanetics DVD which is probably the beginning of the barre genre and led by Callan Pickney. This DVD is exceptionally boring but very effective. It's just for core and legs. Each exercise is pretty much 100 reps but there is a counter to help them go by faster. If you can get over the dread factor of this DVD, it does work.
The good thing about barre workouts is they actually get tougher the more you do them as you learn to use proper form.
As you can probably tell, I love my barre workouts!
Marcy