The instant VOD experience that you watched was downloaded, faster than real time I believe--like a file download, overnight "ahead of time" (much faster than broadband internet DishONLine) and won't show for rental until it has completely downloaded onto your hard drive. Also, the same VOD movies available at the "Movies & More" menu selection are also available at the channel 501 designation. In fact, you will see several channels marked 501. This is the same data (movies/files) that you see with "Movies & More".
Yes, you can order as many VOD's as you like "at the same time". In fact, Dish would love you to do that: more $$$ for them. However, the clock starts ticking when you begin to view the VOD movie.
Now, as a previous poster said, there is DishONLine that provides a different VOD experience. With DishONLine, you select what you want, then the download begins immediately, but you will not be able to watch that VOD event until enough of the content has downloaded. In other words, you can view the event while it is still downloading from your broadband internet connection. However, if you try to watch the event too soon, you will get a message telling you that not enough of the content has downloaded to watch.
In my experience, I have found that it takes less than 5 minutes into the download to watch an SD event. On the other hand, I have found that it can take as long as 10 minutes before you can watch an HD event. You can experiment with the free downloads. You can order as many events as there is room for on your hard drive. The system sets up a queue for multiple downloads and when one finishes, it downloads the next request, finishes that one, then downloads the next request automatically. If you don't have enough room on your HDD for anymore downloads, after several already on the queue, you will see a message informing you so. I have found that there is room for several SD events, but only a few HD events of significant length because HD does take up much more room on the HDD.
I do like DishONLine, and have enjoyed great HD quality downloads, but it is organized very poorly. Everything is organized by title rather than by service. In other words, I would prefers the portal to show all the HGTV On Demand in its own section, and all the MTV content in its own sectiion, all the Food Network shows in its own sections, etc., just like cable does. I often know what I'm looking for by the channel service NOT by the title of the show, necessarily. Someone posted that they had a hard time finding any of the Here! content on DishONLine. That is because all their content is mixed in with all the other junk, and unless you know the EXACT, proper, official title of ALL their shows, you won't find it. So, having a Here! portal would have led that user right to the content he wanted.