The site could use some work in terms of look and feel. I immediately wanted to leave before I even read a single word of text on the site. Looks like it was made in 2002.
Besides that, I like the idea behind the site, and seems like it could be pretty useful. If you want to make this more useful to users, you might want to have training programs rather than dozens or hundreds of random exercises. Someone downloads a plan that says what exercises to do each day of the week, with links to the how-to's, and they are set. Plans are tailored to goals, like running a 5k, running a marathon, putting on 20lbs of muscle, etc.
Same thing with stretches too. I'm a software developer and work on data-driven websites a lot, and obviously I'm into fitness too. PM me if you're interested in working together on this, I'd probably be interested in doing it for free.