When you run a spot in streaming, it plays at a specific point in the video. The two most important placements are called pre-roll and mid-roll. The difference sounds like a detail, but it decides how much of your advertising actually gets through. This article explains both formats, why onescreen deliberately relies on just these two, and why that keeps the completion rate at around 98%.
What is a pre-roll?
A pre-roll runs before the actual content starts. The viewer has selected the show or movie and is waiting for it to begin. That's exactly the moment your spot appears. Attention is high, because anticipation for the content is already there and the eyes are on the screen anyway.
What is a mid-roll?
A mid-roll runs in the middle of the content, at a natural pause, similar to a classic ad break on television. The viewer is already invested in the story and wants to keep watching afterward. That's the big advantage of this placement: anyone who wants to know what happens next stays put and watches your spot to the end.
And post-roll? Why onescreen skips it
A post-roll would run after the content, once the movie or episode is over. And that's exactly the problem: by that point, attention has usually already moved on. Many people switch off, switch apps, or the next episode starts automatically. A spot placed there often falls flat, even though it still counts as an impression in reporting.
That's why onescreen deliberately doesn't offer post-roll, only pre-roll and mid-roll. That way your budget only goes where attention actually is, not on an ad slot barely anyone still sees.
Non-skippable: the ad plays in full
There's another point that makes a difference. On onescreen, spots are non-skippable. Unlike a video on the web or on social networks, where people click away after a few seconds, your spot runs full screen, with sound, and to the end. Your complete message gets through, not just the first three seconds. Why the sound staying on makes such a difference is shown in the article on Sound Instead of Muted Autoplay.
Why the completion rate sits at around 98%
The completion rate, also called view-through rate, indicates how many spots are watched to the end. At onescreen, it sits at around 98%. That's no coincidence, it's the result of a deliberate choice of formats: strong placements in pre-roll and mid-roll, non-skippable, and no post-roll wasting reach.
For you, this means concretely: you pay for contacts that actually happen. Nearly every delivered spot is watched in full, instead of being clicked away after two seconds or landing in post-roll limbo. Why this complete, attentive contact is so much more valuable than a quick impression in the feed is shown in the overview of the premium quality of streaming advertising.
What this means for your advertising
Pre-roll and mid-roll are the placements where streaming advertising plays to its strength: high attention, full sound, big screen, and a message that gets through in full. By skipping the weak post-roll and running all spots non-skippable, onescreen turns an impression into a real contact. How these in-stream formats differ from advertising placed next to or between content is explained in the article In-Stream vs. Out-Stream Compared.
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FAQ
What is the difference between pre-roll and mid-roll? A pre-roll runs before the content, right before a show or movie starts. A mid-roll runs in the middle of the content at a natural pause, similar to a classic TV ad break. Both benefit from the fact that the viewer wants to see the content and therefore stays put.
What is a post-roll, and why doesn't onescreen offer it? A post-roll runs after the content. By that point, attention has usually already moved on, many people switch off or move to something else. onescreen deliberately skips it and relies only on pre-roll and mid-roll, so every contact counts.
Are the spots on onescreen skippable? No. All spots run full screen, with sound, and non-skippable to the end. Your complete message gets through, not just the first few seconds.
What does completion rate mean, and how high is it at onescreen? The completion rate, also called view-through rate, indicates how many spots are watched to the end. At onescreen, it sits at around 98%, because spots are non-skippable and run exclusively in pre-roll and mid-roll.