What is the best cardio exercise for bad knees?

[tanyajack]

Feel Good Knees System is a natural, safe and effective way to treat knee pain. It’s created by an injury prevention expert who specializes in Eastern and Western holistic practices, and who has taken your age into consideration. It doesn’t require you to do anything extreme. Instead, the entire program focuses on simple, gentle movements that can eliminate your knee pain, and rejuvenate and strengthen your knee moving forward. It’s built on a three-level process that must be completely gradually to avoid risk of injury.

http://www.youtube.com/watch?v=4aCA1BKkwKU