The commentary on the video is in German but the gist of this story is that a Spanish truck was joining the Autobahn when he saw what looked like a UFO. He was so startled, that he lost control and ended up on his side. Fortunately, he was not injured.
The “UFO” was in fact a concept house on a low loader that was parked up due to the fact that abnormal loads are normally only allowed on German Autobahns between 22.00 and 06.00.
Bit of German humour here: The investigation will be carried out by the Grünen Männchen (Little Green Men) = Polizei