No. Video footage is stored on a separate hard drive partition. Methods 1–4 leave the HDD untouched. However, a firmware reflash (Method 4) might require reformatting the drive if the file system is corrupted. Always backup critical footage via USB export before resetting.
TrueView DVRs use an algorithm to generate "backdoor" reset codes based on the device's serial number and the current date. trueview dvr password reset
If your DVR supports this, it will display a unique QR code. Open your mobile monitoring app, find the Password Reset tool in the settings, and scan the code. and scan the code.