I know how to remove parts of a video that I don’t want to keep. But is there a way to just stamp it out, cover it up, blot it out. For instance, let’s say I just wanted a big black rectangle to cover up part of a video clip that I would normally just trim completely out of the video. So, that 99% of the view is hidden? A sizeable rectangle popping up on screen would be great. Or even other shapes and being able to choose the colors of those shapes. This way the video remains the same length and there is no perception of a jarring cut in the flow of the video. How can I do something like this with Shotcut?
I don’t know if this is the best way, but it’s pretty easy. Generate a solid colour image (Generate → Color). Put it on a video track above the clip, and use a Size & Position or Size Position & Rotate filter to adjust its size and position to obscure what you want to hide.
A Crop: Rectangle filter or a Mask: Simple Shape would also work to resize the color clip.
If you need to cover an odd shape, you can use Glaxnimate to draw that shape
Generate > Drawing/Animation