Video-editing

Kdenlive

Might want to highlight a particular part of the video, i.e. add a circle on top of existing video to point out some object.
Ideally one would be able to move the image (in the above example, the circle) around wrt. time as appropriate wrt. the video.

Drag-and-drop image into empty space in a video track
- If it's meant as an overlay, then the track needs to have higher priority than the track you want to overlay, of course.
Click on the "image-video".
Add effect "Position and Zoom" (or something along those lines)
[OPTIONAL] To "animate" the overlay, you can make use of the keyframes-functionality:
- Start out with a single keyframe (might require you to delete some existing ones)
- Move the image to the point where you want it to be at the end of the animation/keyframe.
- Click on the "Add keyframe" button once the previous step is done.
- Go to the keyframes you have before the keyframe you just made
- Then move the image, at which point you'll see an "arrow"/line from the final position to the where you're dragging.
  - This line indicates the transition the object will take, thus defining the animation.