Only concerts for which you see "Buy" or "Add to cart" are available for download. If you click on downloads near the top of the page, you'll be able to browse through 100 plus shows you can buy, out of the over 600 that are available for streaming. I don't know what citeria a show must meet before they make it downloadable (I'm not a part of Wolfgang's Vault, just a visitor to the site like you) but they add about 5 new downloads a week.
