It's called Re-use those envelopes and that's exactly what the film is about. Paper waste is one of the reasons why I started Stop Junk Mail (the other reason is of course a dislike dislike of unsolicited, cheap and nasty advertising). And there's an obvious link between junk mail and envelopes; the 4.5 billion pieces of addressed junk mail posted through British letter boxes every year almost all come in an envelope. Re-use labels are a great invention. I post all items we sell in re-used envelopes, saving tons of paper and money.
With Christmas approaching rapidly it might be a good time to start saving your envelopes and getting some of these!