The logic of short-form video: the hook and the retention curve
TikTok, Instagram Reels and YouTube Shorts are different platforms, but they share one logic: a video that keeps being watched gets shown to more people. The platforms do not publish the exact formula, but the message repeated across all three companies' own materials is the same — content people watch, finish, rewatch and interact with spreads further.
The practical consequence: your job is not to accumulate followers but to get the video watched. Those are two different things, and many people conflate them.
The most important number is the retention curve: what percentage of the people who opened the video are still there at each second. Every platform gives you this data, and it shows directly why a video worked or did not.
| Curve shape | What it means | What to fix |
|---|---|---|
| A steep drop in the first 1-2 seconds | The hook fails — people do not grasp what they are seeing | Replace the opening frame and first line entirely |
| It drops in the middle | Long explanation, the rhythm is lost | Cut the middle; shorten by 5-8 seconds |
| It stays flat to the end | The video works | Repeat the format, change the topic |
| It rises at the end | People are rewatching — the strongest signal | Continue this video, make it a series |
The hook — the first one to two seconds. This is the most important part of the video and usually the part least time is spent on.
A hook should be one of three things:
- A problem: "Can't keep up in lectures?" — the ICP recognises themselves
- A result: "This 40-minute lecture turned into eight lines" — people watch to the end to see how
- A contradiction: "I stopped using a voice recorder — here's why" — the unexpected
Hooks that do not work: "Hi, I'm so-and-so", a logo animation, "today I'll show you my app". All three spend the first second on an introduction, when that second is the moment of decision.
An important technical note: the hook is not only words. The opening frame must stop people visually too, because many watch with the sound off. Put text on screen, and never open on a static empty frame.
You will find precise rules online: "keep it under 7 seconds", "use three hashtags", "post at 7pm". These numbers are not in the platforms' official documentation — they are extracted from someone else's experience and go stale quickly. Test them as hypotheses, do not adopt them as rules. The one reliable source is your own retention curve.
Practice. Find ten videos in your category (competitors or the same topic) and watch only the first two seconds of each. For each, note: is the hook a problem, a result or a contradiction? Done means: you have written ten hook lines for your own app — four problems, three results, three contradictions.
📚 Sources and documentation
- TikTok Creator Academytiktok.com
The platform's own educational material on content and reach.
- Instagram: how to growcreators.instagram.com
Instagram's own recommendations for creators.
- TikTok for Business resourcesads.tiktok.com
The platform's own material on formats and creative.