Teleprompter

From Conservapedia

A teleprompter is an electronic imaging system that enables speakers and newscasters to look into the television camera (or at a live audience) and read the text of prepared remarks without the viewers realizing it. It operates like a one-way mirror, with the reflection of text scrolling on the screen for the speaker and the viewers seeing through the text like a transparent mirror.

It was first popularized by former President Herbert Hoover at a Republican national convention, when he gave the secret away by complaining to a national audience that the teleprompter needed to restart the scrolling of the text after he paused to improvise.