Glossary
Pre-roll
A video ad shown before the video the user chose, usually five to twenty seconds, skippable after five. YouTube's main format; also sold by video networks. Bought per view or per thousand.
Also called: video ad, in-stream.
Pre-roll reaches people who came for something else, so the first five seconds are the ad. Affiliates use it for apps, games, iGaming (where allowed) and anything with a demo that fits a short clip.
Mid-roll and post-roll are the same format at other points of the video; out-stream is the video ad that plays inside an article.
Related terms: Display advertising, CPM, Creative.