If the microSD card is not recording videos or cannot automatically delete old videos, please refer to the following steps:
1. Check whether the Xiaomi Smart Camera C700 firmware and the Mi Home/Xiaomi Home APP need updates;
2. Check whether the storage switch is turned off or that the recording mode is set to record only moving images;
3. Format the microSD card within the Mi Home/Xiaomi Home APP;
4. If the Mi Home/Xiaomi Home APP cannot format the microSD card, use a card reader to format it on a computer. After formatting, power off the camera and reinsert the microSD card;
5. If the microSD card cannot record videos, the issue can be related to the card itself. Try replacing it to see if the problem persists.
Does it help?