both bittornado and the azures clinet allow you to select only one or however many files you want to download in a pack. all you do is right click on the file and select the priority, at which point you can select don't download and therefore can select which file you wnat to download and deselect the ones you dont. the process is similar in bittornado i just dont remember specifically what you do.

you can't watch the file you are downloading but should be able to watch it once it is seeding.