Nothing about recording requires a network
Capture, encode and write-to-disk all happen on the device. Apple's own capture stack runs entirely locally, and the hardware encoder in the phone is doing the expensive part. A dual-stream recorder needs a connection for exactly none of its core job.
So when a camera app demands one, the requirement was added, not inherited.
Where the dependency usually hides
The account gate. The most common one. The app records locally but will not open past a sign-in screen. Functionally identical to needing internet, because you cannot get to the shutter without it.
Cloud processing. Some apps upload footage for stitching, stabilisation or effects, then hand it back. That is a genuine technical dependency — and a genuine upload of your footage to somebody else's computer.
The watermark unlock. Recording works offline; removing the watermark requires a licence check against a server. You find out after the shoot.
Telemetry that blocks. Rarer, and usually a bug rather than a policy: an analytics or consent call on launch that has no timeout, so a captive portal or dead connection hangs the splash screen.
The one-minute test
Do this before you rely on any recorder, not after.
Force-quit the app. Turn on airplane mode. Open it cold, record thirty seconds, stop, and play the clip back from inside the app. Then check it landed in your library. A cold launch matters — an app already holding a valid session will happily pass a test that a fresh install would fail.
If it clears that, it will clear a real shoot.
What offline actually costs you
This is the honest half. Fully local means there is no copy of your footage anywhere but your device until you make one. No automatic cloud backup, no cross-device sync, no recovery if the phone goes in a river. Dual-stream video is also large — two simultaneous streams consume storage roughly twice as fast as one, and you are the one managing that.
If you want the safety net, the answer is a deliberate backup step you control, not an app that quietly uploads as it records.
Where Lookout sits
Lookout states it plainly in its App Store listing: offline by design — it works without an internet connection, and 100% on-device, collecting zero data. Recording front and rear simultaneously is done locally on iPhone and Mac, and the app is free.
Which means the airplane-mode test above is one you can run on it in the next minute — and that is the point of a constraint like this. It is checkable, not a claim you have to take on trust.