Storage method and processing device and video recording system thereof

A storage method comprises sequentially storing at least one first media content into at least one first fragment of a storage device, and storing corresponding at least one first media metadata into a first media metadata writing storage window; and when the storage device reaches a storage limit and at least one second media content and corresponding at least one second media metadata are intended continuously to be stored into the storage device, converting the first media metadata writing storage window into a second media metadata reserving storage window to reserve the at least one first media metadata, and sequentially covering at least one second fragment of the storage device with the at least one second media content and storing the corresponding at least one second media metadata into a second media metadata writing storage window; wherein the first media metadata writing storage window follows a first media metadata reserving storage window and the second media metadata writing storage window foll