Short answer: for an exact, unmodified backup of your own upload, use YouTube Studio's built-in "Download" button — it gives you the original file. Use this extension instead when you're working from the public watch page, want a specific resolution, or just don't want to go into Studio for a quick save.
If you're the uploader, YouTube already gives you a way to get your original file back, unmodified:
This is the original file you uploaded — no re-encoding, no quality loss. It's the right choice when the goal is archival: you want the master back exactly as it was.
Use this when any of the following is true:
Keep in mind this path re-encodes the video (fetch + mux to mp4), so for a byte-for-byte backup of your own master, Option A is still the more faithful copy. This side is metered by file size — see pricing.
Neither option here is a bulk/batch tool — each is one video at a time. For backing up an entire channel's history, most creators work through the Content tab in Studio and download each video individually; there's no shortcut around that if you want originals.