I'm trying to draw some geometric shapes on a video as overlay, e.g. draw a box around a part of a video to emphasize. I've seen many videos on youtube that do this, and I'm sure I can do it using commercial packages such as Premiere or AVS video editor. I wonder if there is any free software that can do this?
iMovie comes free with a Mac, and it allows "Picture-In-Picture" images. You can create art with a transparent background, using a free program such as GIMP, then save it in PNG format (not JPG) and then drop it over your video in iMovie.
For emphasizing sections of your video, you can also create a whole image that is partially transparent (like a black image that is 30% transparent) and "remove" a section of it (so the transparency of the "hole" is 100%). It will look like smoky glass with one perfectly clear part. When you lay that over your video, it will look like the rest of the screen was darkened except for the part in the perfectly-clear "window". Kind of a nice effect. :)