Dave commented on a post a couple of days ago that he wasn't ever able to get hizaguruma to work against resistive guys. Here's a handful of hints that might help.
- If you check out the Kodokan Judo book, hizaguruma is shown on page 61. I think the actual action of the throw takes place between photos #11 and #12, concealing the secret of the throw, which is you have to do it on the rear leg instead of the front leg. (as in the video above) Sometime after photo #11, tori touches uke's rear knee, causing him to begin roataing (thus the name of the throw - knee wheel). By the time photo #12 is snapped, uke has already rotated some, giving the impression that tori actually propped uke's front knee. Check out photo #16 for the wrong way to do it and photo #17 for the right way to do it.
- Mifune, in his book, Canon of Judo, demonstrates the technique on pages 48-49. If you check out the accompanying text, I think you'll likely agree that whoever translated the Japanese probably screwed it up because he talks about doing this technique to "the back of the knee" (pure nonsense) when he probably meant "the back knee." Mifune demonstrates it done both ways (front and back leg) but I've never seen anyone who can reliably throw anyone with the front-leg hiza and I've never seen someone who can reliably resist a rear-leg hiza.
- The time for this leg prop is the instant the moving foot hits the ground. Get in synch with any forward step and slip to the side so that your standing foot is lined up with both of uke's feet. Prop his rear leg and pull him 90 degrees to the line you are standing on.
- It helps to think about brushing uke behind you. As he steps forward, you slip to the side, push behind the near elbow and pull the far collar as if just brushing uke behind you - but then trip him onto his face!
- It helps to pair this thing up with a couple of techniques that set it up, like deashibarai and osotogari. The harder they resist hiza, the easier they make it to do osoto. If they resist osotogari strongly, they make hiza more likely.
The following are six books that I recommend as essential reading for judoka. The first three, in particular, reference hizaguruma - check them out!