What does the "Orientation" setting of Locked mode do?

If you tap the settings button (top right), you are presented with the settings options.

The "Orientation" options affects the way the viewport locks in locked mode.

• Auto: Horizontal or vertical orientation will be chosen depending on the device physical orientation. If you start recording, the orientation automatically selected will not change.
• Horizontal: Use this, if you intend to hold your device horizontally.
• Vertical: Use this, if you intend to hold your device vertically.