As a means of communication, video is unparalleled. Our Ballot Box, and later MyMaryland.net needed a short, concise video that explained it's basic functionality.
Neighborhood level activists. Primarily middle-aged plus a roughly equal mix of young adults and seniors. Basic internet users.
Using much of the UX feedback from previous interviews and tests we learned what were the most significant points to explain and the pitfalls around each. Drafts of the video were iterated based on feedback end users.
Apart from the information requirements introductory web videos have a number of unique challenges: Interest in the subject is unusually low so the first couple of seconds are critical to draw the viewer in; they may not have functioning sound or want it; the information/interest needs to stay high, any pause will lose viewers.