The hybrid disc works by making the Blu-ray layer act like a two way mirror, reflecting enough light for Blu-ray playback, but letting enough light through for HD DVD operation.

ENGADGET: Three's company: Warner patents all-in-one hybrid disc HD

Police discovered a false wall in his bathroom with a two-way mirror hiding a camera which recorded girls and women using the toilet or shower.

BBC: Derby

Then he'd have the person stand in front of a two-way mirror looking into the room where a friend of theirs was holding a snake.

CNN: You are the creative type

There was no recording of the interrogation, no one else was in the room or watching from a two-way mirror, and Saldate said he threw away his notes shortly after completing his report.

CNN: STORY HIGHLIGHTS

Beauty brands need to get over their phobia of real research and come out from behind the two-way focus group mirror, where insights are bound to be limited.

FORBES: Wasted Beauty