I recall a Ph.D. program that involved listening to 14 one-hour cassettes and writing a paper on an esoteric topic. One class of programs is more traditional. These require you to spend some time in the neat little rows with Professors on Parade. Some distance education takes full advantage of technology. Lecture notes are published on the Internet.
Diagrams are available.
Short videos can be downloaded. Full recordings of lectures are even available over the 'Net. Although there are more and more universities offering on-line classes, there are technical limits to what can be accomplished. One key limit is the speed of telephone line transmission. Videos with a minute or two of sound take an hour or more to download.