I've done this a few times I like this! It's easy, and requires almost no space. You know, sometimes you just don't want to leave the house (or it's snowing where you live). Also when I walk outside I get distracted, and dilly dally and walk slower, this helps you keep a good pace. I thought this was going to be really easy, but it's actually not that easy. My legs hurt haha. Try it!
Or in fact there are lots of great free videos on Exercise TV