Yes, when you delete an upload from the composer, it is not in fact deleted yet. Upload deletions are delayed and eventually are removed when they aren’t attached to a post.
Sure if you really wanted to re-upload the exact same file then ya you will have to modify it in some way and not just rename it. But for videos even if you re-upload the same file (no modifications) it will re-generate a new thumbnail for it and use the latest one.