D.A. Pennebaker on Depeche Mode
From a 1998 article:

There are three guys: Alan [Wilder] was never really part of the original group, and I think he's out of it now, but he was the consummate musician of the group, so they all turned to him to see that they played the right chords and whatnot. But they really were just three working-class kids who came from a little place outside of London, and they had all grown up together and gone to the same school, and they had doped out together. They had no manager, so they really managed themselves. I mean, they had this guy from Mute Records who would advise them on certain things, but he basically just liked them. He didn't try to tell them what to do or anything. But they had figured out this incredible system for making money where all of their stuff was on a pre-recorded tape, so they didn't need drummers or the rest of the band. And there were really only two of them, because one of them, his keyboard wasn't even plugged in, since he was such a terrible musician. So it was really just two of them doing all this....

And here's something from a 2003 article:

In 1988, Depeche Mode invited Pennebaker and Hegedus to make 101 because they'd seen Don't Look Back....Tipping the scales at just over two hours...101 is indeed big. Possibly even too big. "I thought it should be long, and to this day many people say it's too long," says Pennebaker. "I might be one of them," murmurs Hegedus. But they both agree that Depeche Mode made perfect clients, trusting the film-makers to shoot whatever they wanted and never trying to impose conditions. It's difficult to imagine many major acts following suit in this era of airbrushed image control and kneejerk litigation.

"Often you get the management saying 'you can't do this', and then you have to abandon the film because it's impossible to do it," says Pennebaker. "But we could see Depeche taking all kinds of chances, and it encouraged us to take chances too. The only thing they said was 'you're not going to make us into Spinal Tap, are you?'"