Does the video state the unit is a BM54? Maybe it is a DSP module?

The speaker connections are back there in your car, so that covers one side of the connections (the plugs removed from the BM54 to the loom) but I'm not sure what the other connection would be for (the loom back into the BM54), unless it is to pickup signaling such as the data bus for steering wheel controls, aerial power etc.

You've made me curious now - I'll chase this up later and post back here if I find anything. Links to the video in question and the replacement to head unit you are considering would be helpful. :-)

*edit* - you beat me to it with the link! :-)

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Wayne
2005 BMW X5 3.0d (b 02/05)
2001 BMW F650GS Dakar (b 06/01)