cannot resume downloading movie rental. it just says download error

Hello, willywon.

Thank you for the question. Here are a couple articles that will help you troubleshoot the iTunes Store.

iTunes Store: "Error (-50)" when downloading purchased content

http://support.apple.com/kb/TS1583

iTunes: Advanced iTunes Store troubleshooting

http://support.apple.com/kb/TS3297

iTunes: Possible iTunes Store errors

http://support.apple.com/kb/TS1424

If you received a specific error number or message and the articles above do not resolve the issue, please reply with the specific error that you are receiving.

Hope this helps,

Jason H.