Paste a link to a public video and save the MP4 in full quality.
Instagram streams video and gives you no save button. Paste the link here and the file itself comes back — the same MP4 the author uploaded, with sound, ready to keep on your device.
No re-encoding and no downscaling. The resolution is whatever the author posted.
Audio is part of the file. Nothing is stripped out on the way.
Nothing is stamped onto the frame — the video looks exactly as it does in the app.