I’ve missed this one before, but it was linked at the kraftwerk radio docu page
Radio docu about the Exit festival where Underworld preformed last year.
Also in this one Karl is interviewed about it.

edit: link there is faulty and gives a docu about the Glasgow music scene, I hope they will correct it.
Update: I found another page for the Exit festival docu, link updated. Now the realaudio file is correctly linked.
Update II: Only a tiny bit of Karl and Underworld in it, only the first few seconds of the Exit broadcast we already know.