Original content that you place in your course remains your intellectual property. Because Moodle is password protected, your content will only be shared with the students in your course. However, if you can download it to your computer, so can your students. In most cases, students who do this, don’t do it to share your content, but do so to have a copy in an offline environment for study purposes.
As for placing other copyright material within an online course, use the same respects you would hope to receive. If you are using copyrighted material, ask for permission and give credit. To learn more about copyrighted materials and how to gain permissions, please refer to the UofL fair dealings copyright page.