The media listed in the My content section of your LIBRARY page includes any content you have uploaded. If you are an instructor, it also includes captures from courses for which you are the primary instructor. You are the owner of this content and can edit or share it as you want to.
The Shared with me section of the page contains any media that another user has selected to share with you. You do not own this content; you are simply a publishing recipient from the content's owner.
Hovering over an item in the Library page exposes a menu arrow (also called a "chevron") in the top right corner of the tile, or on the right side of a row if viewing the page in List view.
Click the chevron to see a menu of options, which differ slightly, depending on the type of content selected. The menus shown below are from the My Content section of the page. Shared with me content has fewer options.
Video content menu
Presentation content menu
From the LIBRARY page you can: