Is it illegal for one person to videotape others from a 2nd story apartment over into a adjacent business’s work yard/office?

It is legal if he is videotaping from his own property into an area he can see from his space--just as it is legal to simply look or see anything visible from an area which has the right to be in, he can also video from there.

First of all, you might try and speak with your neighbor about this and express your concerns regarding the breach of your privacy. If they refuse to stop the videotaping, you might consider "self-help" alternatives such as planting trees/shrubs or erecting a tall fence that will give the backyard some cover, and installing blinds for the office. If that fails, then you can call an attorney. The laws regarding such surveillance vary among the states. In some, visual recording is not illegal so long as the camera is on your neighbor’s property or on a in a public place (such as a sidewalk). In others, visual recording is permissable, however audio recording is not. And in still other states, all forms of such recording might constitute criminal and/or civil infractions. As a general rule, any publically viewable areas are fair game (think about Google Street View). Therefore, you may not be able to claim invasion of privacy (but then again you may be able to depending on the circumstances). However, if the videotaping interferes with the reasonable use of your property and is not reasonably justified (i.e. done for purposes of security and/or safety), then it might be deemed a "nuisance" and you may have a claim for damages. At this point, you could consul directly with a local attorney. In fact, a letter from a lawyer might convince your neighbor to cease their snooping, even if you would not ultimately proceed to court with such a claim.