Hi Iphone044,
The exact nature of your concern isn't clear, so here is some information that may help. If not, further details outlining the actions you're taking and specifics may prove helpful for future replies.
If you are attempting to record video through a third party app and it's not working as expected, test the camera in the built-in Camera app and other options to isolate the behavior further. If this only happens in a particular app, ensure the software of your device and that program are up-to-date, and reach out to the developer for additional support if necessary. The page How to contact an app developer can help you reach the right team.
If this is happening in all apps, ensure that your device has available storage, that your battery is charged and not in low power mode, and try restarting the phone. If this continues, seeking service for your device may be necessary.
Regards.