I really like this DVD. I don't have a heavy bag either, and agree that the boxing workout is very solid but not as much fun as her other boxing workouts. I think I would like it better with a bag but since I live in a small 1-bedroom apartment that is not going to happen.
I enjoy the weight workout. She uses both dumbbells and a barbell. I don't have a barbell and I find that subbing dumbbells works well.
However, I generally only use the premixes on the DVD. My favorite premix is the Dumbbell Meltdown premix (43 min including warm-up and cool-down). You do 3 sets of the dumbbell moves separated by boxing. I like this because it eliminates the barbell moves (even though dumbbells work here they are not my favorite moves in the workout) and because alternating the weights with boxing makes the boxing feel much more intense than just doing the boxing workout straight through (although with a heavy bag the intensity is probably amped up). I am a sweaty mess when this is done and feel that I have gotten a really good workout.
I would recommend this DVD, unless you are looking for pure strength. The weight segments move too fast to go heavy and are more for a cardio effect. I use a pair of 10-lb dumbbells and find that works well for me (I consider myself to be a solid intermediate who is moving toward a high-intermediate level).
Hope that helps! Let us know if you try the workout and what you think of it.
Steph