Decoding videos from Eufy 2k

IT seems to be impossible to download a continuous recording from a hole day. If I look at the SD Card (it is Ext4 filesystem and can be read at all Unix PCs), I see the recording as dat-files. How can I transcode them to mp4?

You can’t. They are encrypted. The only thing you can read from the card are log files. That’s why you need the app to provide keys to unlock your clips.