Videos can be good - it depends which one oyu've got and if you do it! I reckon if you can do water aeoribs 3 times a week and walk/jog in the arvos then you'll be better off doing a weights program than more cardio.

Resistance (weights) training is a really important part of weight loss which a lot of women overlook becasue they are scared they'll get bulky - you won't, unless you're taking steroids Low weights, high reps will improve your lean muscle mass which will improve your metabolism, helping you burn more KJ's. You can buy weights pretty cheap from Kmart, Big W etc even the supermarket. I bought a set of 4kg dumbells for $10 in Coles the other day.

Once you've got the weights I can give you some exercises to do if you like. 3kg and 4 kgs would be good to start with, let me know