Add a "Primitives" or "Shapes" section for annotating the video.

[raindropsfromsky]

Often we need to annotate a video with shapes.

For example, to point out a person or object in the video (with an arrow, circle, oblong, rectangle, polyline, or polygon)

We may want to make this shape static or animated.
Typical examples:

• An arrow that appears tail first, and extends towards the arrowhead
• A circle that reveals itself in clockwise/anticlockwise around the object of interest (as if drawn by hand)
• A rectangle that is wiped in, after which some text appears in it.
• A polyline that traces a route, and appears segment-by-segment
• A polygon that traces a shape, and appears segnemt-by-segment till it outlines the enclosed shape

All these tricks are possible, but it takes a lot of effort.
These assets should be provided by default, with some default animation built in.
Let the user edit the effects.