What is a Promo video

Everyone knows what a promo video is, its a video that promotes somthing, but if you try and find a 'standard' promo on the internet it's fairly tough, because there is no real correct structure to a promo video, it's one of the very few kinds of video that pretty much anything goes.

one of the most effective videos i could find, was the o2 priority advert

I think the video is effective because it's so basic and tells you the bare minimum and tells you where you can find out more if you need to. the main point about the advertisement video is that it builds up tension, which helps to keep the audience interested in the advertisement, and the promotional video too. I think some of the shots used are really effective and help to keep the audience interested.