I am not sure that a factory BMW TV adapter harness exists. At least, I have never seen a part number for one. Here is a post that explains how to use a navigation adapter harness part number 61 12 8 377 436 to create a TV harness. This is the approach that most people use. It is relatively inexpensive and works great.

http://openbmw.org/nav/sys/index.html

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SOLD
2000 E38 750iL Highline Edition, Upgraded with the lastest 2006 X5 Electronics
MKIV Navigation, 16:9 Display, Bluetooth, TV/Video with Backup Camera, Sirius, and Aux Input