Look at the following case, which I was principal defense counsel in. http://www.state.il.us/court/opinions/appellatecourt/2005/2nddistrict/april/html/2040170.htm You'll see that you don't have an expectation of privacy in your yard that will serve as the basis for an injunction preventing your neighbor from taking video of you. And, it's not a crime to film something outside, even if it's in your back yard. However, if he films inside your house, that is a criminal act and would be something you could get a court to enjoin.
Of course, he can never use an audio recorder, as that would constitute criminal eavesdropping under the current statutes. Hope this helps, but you may well wish to discuss the specific facts with a local attorney knowledgeable in this area.
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