Good slower ball for Prior, I was wondering when that was going to pop up. It's also ideal for Johnson to bowl at Flintoff if he can produce a few sharp short balls.
Back to Bell, I don't know if you can really attribute Bell's problem to technique or a small weakness in a particular area. Sometimes he's just really bad at making decisions. He can be seen trying to get onto the front foot against short balls, but then he doesn't always get forward as much as he should, as in his dismissal. He might look likely for lbw, but if you bowl wide at him on a good length, he'll have the odd dip.