Years and years ago I thought that doing aerobics tapes holding 8 pound dumbbells would be a great way to combine strength training and aerobics...and get it all over with at the same time. This was years before I actually had any training and became certified
I did this everyday for months, and gradually upped my weights. I did lose more weight, but my shoulders started to ache. Then hurt. Then it got to the point that I couldn't hold a heavy pot, pull up my pants, or swing a tennis racquet.
What I did was create small tears in my rotator cuff muscles and massive tendonitis from overuse. Your body isn't designed to constantly swing more weight from your shoulders. When you lift weights, you do maybe four to eight sets of 10-15 reps of a few arm exercises. Even lifting a different body part each day, if I spend half an hour a week doing pure bicep exercises, that's a lot.
Contrast that with walking or doing an aerobics tape holding weights everyday for 30-60 minutes and you can see the kind of stress that you are putting on your shoulders.
IMO, you're better off doing the walking/aerobics and then some weight training. The two are different types of exercise and you really should incorporate both
Mel