Quicktime screen recording - capturing dual screens?|Quicktime螢幕錄影能否同時擷取多螢幕?

During initial region selection, it may appear that Quicktime allows you to describe both screens for recording, but this is deceptive. The result video clearly shows that only one of the two screen was captured, not both.

Quicktime also has the "whole screen" option. Upon recording, it prompts you to choose either screen 1 or screen 2, but not both.

In conclusion, only one of two screens can be captured any given time.