When you’re done editing, you need to save your video. Here, you have two options: Save, and Save As.
Select Save, and you will be changing the original video to the newly edited one. The URL will stay the same, and all references to the video through links and embeds will point to the new video you’ve just edited. If you save your video this way, you won’t be able to access the original file through YouTube, so make sure you have a backup copy on your computer.
Select Save As, and your edited video will be saved as a new file with it’s own unique URL. Your new video will automatically include the same titles, tags and description of the original, but these, and other video settings, can be edited.