idler pulley will squeak (didn't listen to your vids though). Cheap and easy to replace. If it is the tensioner pulley, you can usually get those separately too. Don't have to buy the whole tensioner assembly.

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Kirk
Las Vegas
2016 X5 40e Mineral White/Black Dakota Leather, ZLL, ZCW, ZDA, ZDB, ZPP, multi contour seats, rear side window shades, HK stereo
2011 E90M3, 6-speed manual