I wasn't sure either at that price! In the end I went for it and do NOT regret it they are awesome!
This video show nicely how the lights work from about half way through.
https://youtu.be/CBUYm5AghVI
PS how do you embed a youtube video into your posts?
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BMW M4 - Tanzanite Blue, Silverstone Full Merino Leather, M DCT, Comfort Access, Reversing Camera, Sun Protection Glass, Extended Storage, Armrest with sliding adjustment, Interior trim finisher - Pearl Chrome, Adaptive LED Headlights, High-Beam Assistant, Surround-View Camera, M Head-up Display, Harman/Kardon Surround Sound, Internet, Online Entertainment, Speed Limit Display, Piano Black Interior BMW Individual.