Hello,
Thank you for the .gif, however, on it, I can see it the screen selection for "Capture" popping up immediately which is as designed.
The idea is with either screen capture or recording, to allow selection and begin actual recording when its clicked on, whether that is an entire screen or some part of it.
The delay is supposed to be applied once the selection is clicked on, e.g on the .gif after you clicked on the area Toolbox normally would have an icon of the capture in the Dock with numbers ticking down, and actual screenshot\or video would begin recording with a set delay.
Since I cannot see that occur on the .gif, can you let us know if it doesn't work as described for you, and if the actual capture begins immediately, and if so, what frequency of occurrence?