They are doing mixing live. That is the whole DJ thing, you know plenty about that already. I can tell you that track by Kraftwerk isn't not perfect to the album (I think it uses some different samples), but it isn't going to be mixed by a producer and that song is 33 years old, so I imagine it has changed a bit when they perform it over the years. That is pretty much what the whole house music scene is about and part of what makes Daft Punk awesome (You have listened to Alive 2007 sometime yeah?).
That isn't to say there isn't DJs that mix all their shit before an event and stand in a booth with headphones on and just play with switches and buttons all night just for show though.