Sometimes, due to accidental setting changes, the video playback may show audio only with no image, or video playback may be restricted due to vehicle safety regulations (video-in-motion protection).
After confirming it is not related to account or app permissions, you can try the following settings to restore video display:
For 7862 (4+64G / 8+128G models):
Go to:
Settings → Factory Settings (password: 3368) → Protocol Options → Brake Wire for Video in Motion
Turn this option ON / OFF to enable or restore video playback.
For 7870 (12+256G models):
Go to:
Settings → Protocol Options → Brake Wire for Video in Motion
Switch this option ON / OFF to restore video display.
Note:
This setting controls the video-in-motion safety restriction.
If video is still not displaying properly, try toggling the option again or reboot the unit after changing the setting.