Well of course its "illegal", and from what I seen the quality sometimes suffers for it.
But the guy spends an inordinant amount on comics as is, keeping up with his favourite titles, and he was obsessed with wanting back issues, but confronted with his own financial reality.
So he took up downloading torrent packs, and seriously has about 10,000 Marvel comics, which imo, he'll never get around to reading 10% of.
I don't know how much the DVD cost, but I've heard each page has Marvel watermark on it, and if you really want to get the back issues, you'd have to be rich.
Plus for the most part it isn't money out of Marvel's pockets, as Marvel has already made their money on these titles, it just probably makes it harder on comic shop owners and collectors short on cash.