This is the question that decides whether the link you have works on this page. The three formats use the same player and the same kind of address, but they were born in different corners of the platform.
A feed video is the video published on the profile, in the same place as a photo. It is permanent, shows up in the grid, carries its own audio and tends to run much longer than a Reel. It is the format of interviews, lessons, recipes and podcast clips.
Reels is the short vertical format, built for the discovery feed. It gets its own treatment inside the app and its address starts with instagram.com/reel/. If all you want to save is a Reel, use the
Instagram Reels downloader — the process is identical, but
that page deals with that format specifically.
IGTV no longer exists as a separate format. Instagram discontinued it in 2022, and content published there became Reels or feed videos. An old instagram.com/tv/ link can still open in the browser, and this page can read that address too — but inside the app, that video already appears as a regular post.