Are you the type of designer who wants to know how your tools work, or are you only concerned with the utility they provide? If you're the former, you're bound to find the following video interesting. TechQuickie breaks down the difference between JPEGs, PNGs, GIFs, TIFFs, SVGs and Raw files, and the tricks each format uses to balance image quality with file size:
Sadly there's no comprehensive video on the variety of modern-day CAD file formats. Best we could dig up is this rather bizarre video explaining the difference between IGES and STEP files.