Abstract: When recording an inventory, a video-camera having a microphone and optics making possible total views, as well as detail views on a larger scale of the individual objects is used. When the recording is terminated the cassette is sealed by means of a cylindrical body introduceable in a cylindrical passage in the cassette casing, the body being provided with at least one extending lip engaging an opening in the side wall defining the passage. The mechanism includes at least two portions interconnected by a fractural impression so located that a fitted mechanism cannot be removed until the two portions have been separated. An arm directed sidewardly from the body may carry a member at its distal end adapted to lock the lid of the cassette. Alternatively the cassette is placed in a cover of radiation impervious material, which is sealed together with the cassette.