Same video, different label
MOV is Apple's container, and iPhones and Macs produce it by the gigabyte. The footage inside is ordinary H.264 or HEVC — the same thing MP4 carries — yet Windows apps, Android phones and half the web's upload forms reject the file on sight. The incompatibility is the box, not the video.
So this tool usually just changes the box: a remux that finishes in seconds and leaves every frame bit-identical, because nothing was re-encoded. When a MOV carries something MP4 genuinely cannot hold — old QuickTime codecs, editing-oriented formats — it falls back to a real re-encode automatically.
Family footage stays home
Videos of kids and holidays are the files people least want on an anonymous server, and classic converter sites ask for exactly that. Here the file is repacked by your own browser and never leaves the device.