Hi, I am sorry to hear of your troubles with video recording, and can understand your frustration. Having trouble with unresponsive apps? It may be time to give them a good spring cleaning. Don't worry, you don't have to uninstall the app or reset your phone. Instead, clear the app's cache or data. When you do this, any problematic files or bugs in the app will be deleted. You can also use your phone's Device Care features to limit background apps and help your battery last longer. Try these steps: https://www.samsung.com/us/support/answer/ANS00077611/
You can also try wiping your device's cache partition if that does not resolve it. The steps are:
Performing a wipe cache partition removes any temporary files that may be causing an issue with the device. All personal files and settings are not affected by this option.
- Ensure the device is powered off.
If the device is unresponsive/frozen, press and hold the Power button (located on the upper-left edge) for approximately 10 seconds or until the device power cycles.
- Press and hold the Volume Up button (located on the upper-left edge) and the Home button (located at the bottom in the middle).
- While continuing to hold the Home and Volume Up buttons, press and hold the Power button (located on the right edge) until "RECOVERY BOOTING" appears in the upper left then release all buttons.
- Select wipe cache partition.
Utilize the Volume Up/Down buttons to highlight and the Power button to select.
- Select reboot system now.
Option is highlighted, utilize the Power button to select.
Finally, you can see if possibly a third-party application is to blame for messing with functionality of the Camera app. This guide will have everything needed for using Safe Mode: https://www.samsung.com/us/support/answer/ANS00062983/
Please let me know if these steps helped.