Pre-roll ads play automatically before online videos (such as YouTube content) and are usually 15 or 30 seconds long. 60-second pre-roll is unusual but not unheard of; most consumers find it intolerable.
Sandwiched in the middle of video content and loathed by consumers, mid-roll ads are a minimum of 12 seconds.
Post-roll ads play automatically after videos and are typically 10 to 15 seconds.
