Videos, websites, and design are easily understood but I'm not quite sure what you mean by problems. I also have videos as one of my topics/categories/sub-categories...
Problems is something that would probably be specific to my physics classes. What I mean for that category is that I am looking for downloadable worksheets or just plain websites that have problems for students to solve.
VIDEOS: instructional, anticipatory set, closure
PROBLEMS: downloadable, online
WEBSITES: articles, simulations/virtual lab, instructional, data
DESIGN: images, sounds, fonts, tools