There are many different ways of using commercials. You will probably think of TV first of all. This makes sense, because TV is still a very important medium for reaching a very large number of people at once.
But in the online world too, commercials are gaining more ground. Not only is it far easier to measure the effect of online commercials, you can also encourage the viewer to action in an efficient way by using clickable links.
Because online advertising is more focused, offering user-relevant content, the likelihood of the viewer experiencing the commercial as an intrusion is considerably less. After all, it suits their interests. This makes online commercials more targeted.
In addition, online commercials are cheaper to produce, enabling you to get more video out of your budget, or launch several campaigns for the same amount you would spend on a TV commercial.