I saw questions about this, but haven’t found a feature request, so here it is:
It would be nice if the optimization feature allowed user to delete the original video file and use the optimized file instead. That would help save space. Since there may be multiple optimized versions, for each optimized version, it’d be nice to have an option to use it as the original. I’d recommend saving a backup of the original, just in case something goes wrong with the optimized version (this can also be an option: delete original after optimization is complete).