Android makes this painless. The download goes straight to your phone — no share sheet detour needed.
Saved
Copy the link in the Instagram app. Tap the three dots on the video and pick Copy link.
Open ReelGrab in Chrome (or any browser). Paste the link, tap save. Android downloads the MP4 in the background.
Find it in your Downloads or Gallery. Most Android phones add new MP4s to the gallery automatically. If yours doesn't, the file lives in the Downloads folder.