Downloading music without paying for it is theft. It might be justifiable at the margins - bootlegs, impossible to find tracks etc - but other than that it is theft. Music is still hugely expensive to make professionally, despite the computer age. I know there's a generational divide here, but it is what it is. And second-hand records have at least been paid for in the first place.
As far as the ad goes, I think it's great that some of David's more difficult work is getting commercial exposure. If it leads someone to think 'wow, what is that music' and to start to explore the Sylvian catalogue then that's great.