In DC pre-5.2.0 the only downloaded file names, which could be configured as the original file, i.e. media format ID 0. This has been altered in DC 5.2.0 so that all downloaded files' names will adhere to the digizuite configuration.
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An example of a configured value is "[%AssetTitle%] - [%OriginalFileName%] - [%MediaFormatId%]", which will result in the file name "my new title - ferrari 3d mock - 50033.jpg". Only the known names will be replaced, i.e. "[%AssetTitle%] - company name - [%MediaFormatId%]" will result in the file name "my new title - company name - 50033.jpg".