You can purchase a movie at any time by clicking the gray "Buy Movie" button next to the title. When you click "Buy Movie" a window will pop up asking if you're sure you want to buy the movie. When you click Yes, iTunes charges your credit card for the purchase and the movie begins to download immediately. When your movie starts to download, you will see a little green page icon called "Downloads" appear under "Store" in the left-hand menu column of your iTunes window. Click on this to see the progress of your download. It will tell you how much has downloaded and how much time is left before the movie is complete.