This a great exercise that I've seen done by a number of different strength coaches and trainers. It's a great bang for your buck exercise that could be worked into your warm up. You're getting in some hip mobility, some shoulder mobility and some thoracic mobility. It's basically a few movements thrown together: push up, downward dog, striders and thoracic rotation.
When I was first introduced to the Valslide leg curl a few years back I loved the exercise but the question I had was how to progress the exercise. I just didn't want to keep adding reops just to make it harder. It didn't take me long to figure out different progressions whether it was using a band for resistance, using weight plates for resistance or going to single leg versions.
Hereis another a version I just started using, the cable resisted version. All you need a is a low pulley or two. Then strap in to a couple of ankle straps, place your feet on a couple Valslides and go to work.