Checking for purchases in iTunes!
If you purchase videos or files on iTunes that are large to download, you might not always have time to download the whole file. You can resume downloads with iTunes purchases though. If the download is not done, you can even restart the whole download. To do so, you just have to right click on the "Purchased" list in iTunes and choose "Check for purchases...". It will connect to iTunes, ask you to log in if you are not logged in and check if you have any purchases that weren't downloaded. Backing up is a must once files are downloaded though, because you won't be able to redownload once the download is completed.