Piece to camera
Also called: PTC, direct to camera, talking to camera
Borrowed from broadcast, a piece to camera has the presenter address the audience directly instead of talking to an off-camera interviewer. On YouTube it carries the hook, the introduction, the argument and the sign-off, which makes doing it without stiffening up the single biggest on-camera skill a creator can build.
The difficulty comes from the absence of a person. A lens gives no feedback, so people either freeze or start performing. The usual fixes are practical: put the lens at eye height, picture one specific person you are explaining this to, and get the first take out of the way knowing you will throw it away. Autocue helps some presenters and makes others look like they are reading, which they are.