Several things; a) Proper spelling. You should use it. b) You might have a slow internet connection, or you might have some loose wires. Are there any storms in your area currently? c) It's longer than your average episode of DW, clocking in at 50 minutes in itself if I remember correctly. d) Why did you buy it off ITunes? >_>
And that full 135 minutes will tug at your feels like never before. Prepare for all of your emotions.
Piracy is not stealing. It is someone else taking something they bought, copying it onto a hard drive they bought, and giving you that copy for you to put on a hard drive you bought... Neither you nor the one who gave it to you interacted with the company after the original sale, let alone stole from it.