A documentary based advert will have lots of facts shown during the advert, all that will be shown will be hard facts that can be proven. A 'documentary' advert will be very informative. The advert can be quite a relaxed theme or quite grown up. Obviously this would also depend on what time it would be shown. An advert that would be shown anytime would be sensodyne toothpaste advert.
This advert has people who have had trouble with their teeth being sore after eating/drinking and how sensodyne changed that for them. This is promoting the product and is using facts.
This type of advert will always attract a big audience as it's well known audiences believe things that as an advert like this is broadcast on TV then it must be true. Not many think to actually check whether it is true, the viewers will automatically think it's true due to the way the advert is set out and because the advert has people speaking backing up the advertised product.
