Firstly, thanks for uploading it to your own servers Soren.
I am having the same problem with this firmware update as I did with the previous one. Firstly when trying to update, it says 'Firmware invalid' or something to that effect. Then, I try it again and it never progresses past 'Find and check firmware'. Last time I just kept restarting the DX50 until it managed to find it, so hopefully this works this time around.