. . . . create call-out annotation where the text is fixed and the extension line will follow the moving object. . . . .
This one will have to be done manually, key framing the length and position of the end of the extension line from the text to the subject using an image for the extension line, or using Xara Photo & Graphics Designer, if you have it, to create an overlay.
MEP's Attach to picture position in video works like this
Ain't gonna happen. It can be done using programs like After Effects and HitFilm, but not by normal video editing programs as far as I know. As John EB said, this can be done by using Xara Photo & Graphics Designer or Xara Designer Pro from MEP using the animation feature of Xara, and you have to move the line end point to follow the action. There are not many programs that have this kind of feature. Xara does vector graphics that can be animated and tweened, video programs do not normally do vector graphics.