Ignore the black area near the top: when I enable dual-head with xrandr --auto my monitors have their bottom edges aligned, and since the internal LCD panel is shorter, and Kazam records the top-left 1280x800 area of the combined 2560x1024 desktop, you get that black bar.
Here's a screenshot demonstrating the problem.
Ignore the black area near the top: when I enable dual-head with xrandr --auto my monitors have their bottom edges aligned, and since the internal LCD panel is shorter, and Kazam records the top-left 1280x800 area of the combined 2560x1024 desktop, you get that black bar.