Of you go down the camera route, just be careful of the cheaper ones - the software can be more of a problem than the camera, especially if you want to share it.
I'm not sure that a camera is the solution though.
Have you checked if there is a person/authority in charge that you can talk to about this?
Maybe, she's not aware of the rules and is elsewhere posting about a cyclist who keeps trying to run her down?
In an ideal world, you'd stop the next time you see her and calmly explain the rule(s), that you're training and it's really frustrating when people get in the way.
If that's not an option could you ask another cyclist, prefereably female to have a friendly word? Or maybe talk to one of her friends if they seem more approachable.
A camera won't stop things escalating, might be of some use if she jams a stick in your front wheel and won't be a lot of help if her boyfriend/brother/father jump you some night.
Good luck!