Today, the CCD S820 manual is not a manual. It is a myth. Original copies, when auctioned, fetch more than the camera itself ($4,200 for a mint manual vs. $1,800 for a working S820).
This is the core function. The camera records video in segments (usually 1, 3, or 5 minutes). When the SD card fills up, it automatically overwrites the oldest unlocked files. This works reliably on the S820, ensuring you never run out of space. Ccd S820 Manual