Privacy laws vary somewhat between different states, but taking a picture or video of someone without their consent or knowledge in a private residence is an almost-universal example of a violation of privacy. A related violation of privacy would be hacking into a personal account and viewing or distributing material from it, which happened with a number of candid celebrity photos.
Taking a photo or video of someone in their private residence always requires their consent. Consent to enter someone's home does not imply consent to photograph. Some legal provision is made for business owners to use video surveillance in the public areas of stores and hotels to protect their business, but they are often required to disclose that they are recording on the premises.
While states generally allow surreptitious video recording in property that a person owns, such as hidden cameras designed to detect intruders or secretly monitor babysitters and housekeepers, a number of states require all parties involved to be aware of and consent to audio recordings or it is legally an invasion of privacy. This is the case in California, Connecticut, Delaware, Florida, Hawaii, Louisiana, Maryland, Massachusetts, Montana, Nevada, New Hampshire, Oregon, Pennsylvania and Washington.
Regardless of local laws, an individual who is being secretly recorded or photographed or having materials thought to be private distributed without their consent is very likely to consider these actions an unacceptable violation of their privacy.