An AI chatbot is a fast way to write captions, opening hooks, short video scripts, titles and descriptions. Tell it the platform, what the video shows, who it’s for and the tone, and ask for several options. It won’t know what’s trending today, and its first drafts can sound generic, so treat them as raw material. A language model on your phone does all of this offline, which helps when you’re filming somewhere with bad signal or working on content you can’t share yet.
This is the writing side of video. For the editing side, like cutting clips and adding subtitles, you need a video editor, and we cover how that differs below.
What is AI good at for video content? #
| Job | How well AI does it | Tip |
|---|---|---|
| Caption variations | Very good | Ask for five in different tones |
| Opening hooks | Good | Ask for hooks under 10 words |
| Short scripts with shot lists | Good | Give length in seconds and the key message |
| Titles and descriptions | Good | Give the main keyword you want in it |
| Repurposing a long video into short ideas | Good | Paste the transcript |
| Trending hashtags and sounds | Poor | It can’t see today’s trends |
| Knowing what your audience likes | Poor | Only you and your analytics know |
Prompts for captions #
Caption options by tone
Write five Instagram captions for a video of me making sourdough for the first time and it collapsing. Tones: self-deprecating, encouraging, deadpan, informative, one-line. Under 30 words each.
Adapt one caption per platform
Here’s my caption: [paste]. Rewrite it for TikTok (short, casual), LinkedIn (professional, one lesson learned) and YouTube Shorts (curiosity-driven title plus one line).
Caption from a photo or frame
Here’s a screenshot from my video. Suggest three captions that match what’s happening, and one question to ask viewers to get comments.
With a vision-capable model, you can attach the frame instead of describing it.
Prompts for hooks and scripts #
Hooks
Give me 10 opening lines for a 30-second video about three mistakes beginners make with houseplants. Each under 10 words, and none that start with “Did you know.”
Short script with shot list
Write a 45-second script for a video explaining how to fold a fitted sheet. Format it as a table with seconds, what’s on screen and what I say. Keep the tone friendly and fast.
YouTube title and description
Suggest eight titles for a video reviewing budget hiking boots, under 60 characters, including the phrase “budget hiking boots.” Then write a 120-word description with three chapter timestamps I can fill in.
Repurpose a long video
Here’s the transcript of my 20-minute podcast episode: [paste]. Suggest five ideas for 30-second clips, each with the timestamp range to cut and a hook line.
To get a transcript from a recording without uploading it, see offline speech to text on your phone.
Accessible descriptions
Write a one-sentence description of this video for viewers who can’t see it, and alt text for the thumbnail.
What about hashtags and trends? #
A language model’s knowledge stops at its training date, and a model running offline has no internet at all. It can suggest sensible, descriptive hashtags for your topic, but it can’t tell you what’s trending this week or which sound is taking off. Check the platform itself for that. We explain the cutoff in can offline AI know current events.
Keep your voice #
Audiences can spot generic AI captions quickly. A few habits keep yours sounding human:
- Give it your past captions and ask it to match the style.
- Ban your pet hates: “No emojis in the first line,” “never say ‘game-changer’,” “no questions as hooks.”
- Pick, then rewrite. Choose the best option and change the wording yourself.
- Save your brand voice in a system prompt so every chat starts with it. Our system prompt examples show how.
AI writing tools vs AI video editors #
AI video editors handle a different job: auto-subtitles, cutting silences, reframing for vertical video, background removal and effects. Some of that runs on the phone and some is processed in the cloud, which means uploading your footage. Check an editor’s description and privacy policy before you rely on it for unreleased or client footage. For the photo side, see which AI photo editing tools work offline.
A chat app doesn’t edit video or generate subtitles from audio. It writes the words around your video, and for that, a chat is often faster than an editor’s built-in caption tool because you can iterate freely.
Write captions and scripts offline #
Personal LLM runs AI models on your phone, with no account and nothing uploaded, so it works on location with no signal and keeps content that isn’t public yet off other people’s servers. Attach a frame or a thumbnail and a vision-capable model can describe it and suggest captions. Save your brand voice as a chat’s system prompt, use the Creative preset for hooks and caption variations, and copy any result in one tap.
The limits are the ones above: no trend data, no web access, and a phone-sized model’s first drafts need your edit. For quick caption options and script outlines, that’s usually all you need.
Frequently asked questions #
Can AI write Instagram or TikTok captions? #
Yes. Describe the video, the audience and the tone, and ask for several options. You’ll get the best results by giving it examples of your past captions and editing its drafts before posting.
What’s the best free AI caption generator? #
Any general chatbot works well if you give it good details. A free on-device app like Personal LLM works offline and keeps your drafts private. Cloud chatbots such as ChatGPT or Gemini have free tiers too.
Can AI generate hashtags? #
It can suggest relevant, descriptive hashtags for your topic. It can’t tell you which hashtags are trending right now, especially when running offline, so check the platform for current trends.
Can AI write a video script? #
Yes. Give it the length in seconds, the key message and the tone, and ask for a table with timings, what’s on screen and what you say. Read it aloud before filming; spoken rhythm is where AI scripts most often need changes.
Do AI video editing apps upload my videos? #
Some features run on the phone and others process your footage in the cloud. It depends on the app and the feature, so check the description and privacy policy, especially for private or client work.