Don't feel bad. Lots of people do it and lots of sites don't mind (or they'd make it difficult). Most people don't know about bandwidth and some of the details of how the Internet "works". It use to be worse several years ago because things were just beginning so how to charge for stuff and how it was put together and "size" of things was more important. Now with faster machines and more storage space, cheaper, etc. it's not as big a deal.