The Motion Picture Association of America and the National Association of Theatre Owners on Wednesday said that movie theaters should ban smart watches or eyewear that could be used to record movies. They have both updated a film-theft prevention policy to recommend zero-tolerance when it comes to movie goers wearing "smart" devices with video-recording capabilities.

Theater operators are free to embrace or ignore the guidelines.

Google Glass, which has triggered concerns about privacy since the devices are capable of capturing pictures and video, became available in the United States in May to anyone with $1,500 to spare.