How to Generate B-Roll With AI

B-roll is the footage that holds a production together. It covers jump cuts, sells a location, and gives viewers something to look at while narration or dialogue carries the story. For most of film history, getting good b-roll meant sending a camera crew somewhere or licensing stock clips. AI changes that math — you can generate custom b-roll from a text prompt in under a minute.

This guide covers what AI b-roll actually is, how to prompt for it effectively, which models to use, and where free stock footage still beats generative video.

What B-Roll Is (and Why It Matters)

The term comes from the days of physical film editing, when editors worked with two reels. The A-roll held the primary footage — interviews, main action, on-camera dialogue. The B-roll held everything else: cutaways, establishing shots, reaction shots, illustrative footage.

That structure still describes modern editing. Your A-roll carries the core story. B-roll does three jobs: it illustrates what the narration describes, it hides editing seams and jump cuts, and it controls the visual rhythm of the piece.

In a micro-drama context, the distinction blurs a little — every shot is intentional, not an afterthought. But the principle holds: you need shots that aren't your main character talking to camera. Establishing shots, environmental details, atmospheric inserts. That's where AI b-roll earns its place.

Which AI Video Models Generate B-Roll Well

Not every video model suits every type of shot. Here's how the current options break down.

Veo 3 (Google) produces up to 8-second clips with strong motion coherence and native audio generation. It handles atmospheric and establishing shots particularly well — wide cityscapes, natural environments, abstract textures. If you need a clip that reads as cinematic rather than AI-generated, Veo 3 is the current benchmark.

Kling (Kuaishou) is cost-effective and produces solid motion quality. Good for lifestyle b-roll, interior environments, and shots where you need volume without burning budget.

Seedance (ByteDance) sits between the two on price-to-quality. Useful when you need consistent motion on a subject across multiple clips.

On Leyline's platform, these models are available directly in the Videos step. You generate from a keyframe — a still image that controls composition and screen direction — which gives you far more control over the final clip than a text-only prompt ever could.

How to Write Prompts for AI B-Roll

The single biggest mistake with AI b-roll prompts is being vague. "A city at night" will get you something generic. Treat each prompt like a brief to a camera operator.

Specify the shot type first. "Wide establishing shot," "close-up of hands," "aerial drone view looking straight down" — the model needs to know where the camera is before it figures out what to do with it.

Describe lighting and mood explicitly. "Golden hour, long shadows" and "overcast, flat grey light" will produce completely different shots of the same subject. Don't leave this to chance.

Keep subjects impersonal when possible. B-roll showing hands, objects, environments, and crowds is easier to use commercially than footage of recognizable faces. It also tends to generate more cleanly.

One action per clip. The prompt "a busy street where a woman hails a cab while it rains and neon signs reflect in puddles" is four prompts fighting each other. Pick one: the woman hailing the cab, or the puddle with neon reflections. Generate them separately and cut between them.

Generate multiple variants. Ask for three to five versions of each shot. AI video generation has variance — the second or third clip is often meaningfully better than the first. This is especially worth doing when you're writing AI video prompts for the first time with a new model.

Prompting for B-Roll Inside a Production Pipeline

On Leyline, the cleanest workflow runs like this:

1. Finish your Breakdown step so you know exactly which shots need coverage.
2. In the Assets and Keyframes steps, build reference images for any b-roll shot that needs a specific look — a location, a prop, a color palette.
3. In the Videos step, select your model (Veo 3 for high-fidelity atmospheric shots, Kling for cost-effective volume), attach the keyframe, and write a specific prompt.
4. Generate multiple variants, pick the best, and move to Export.

The keyframe is doing the heavy lifting on composition. Your prompt then handles motion, duration feel, and atmosphere. That combination gives you b-roll that actually matches your production's visual language instead of looking like a random stock clip dropped into the timeline.

When Stock Footage Still Makes Sense

AI b-roll is better for custom, branded, or setting-specific footage. Stock is still faster when you need something generic and your time matters more than visual distinctiveness.

For zero-cost stock b-roll, Pexels and Pixabay cover most use cases — both are CC0, commercial use is fine, no attribution required. Mixkit is the pick when you want polished lifestyle or tech footage without any attribution hassle. Coverr is smaller but curated, good when you'd rather have ten great clips than a thousand mediocre ones.

For 4K nature and aerial footage without a drone or a budget, Dareful is CC0 and genuinely high quality. Storyblocks makes sense for agency-volume workflows where you're downloading dozens of clips per project.

The honest read: stock footage increasingly looks like stock footage. For anything brand-specific or narratively precise, generating with Veo 3 or Kling will produce something that feels more intentional. If glitchy output is a concern, see the guide on how to fix glitchy AI video clips before committing to a model.

Frequently Asked Questions

What is AI b-roll?

AI b-roll is supplementary video footage generated by a text-to-video or image-to-video model, used the same way traditional b-roll is used in editing — to cover cuts, establish locations, and add visual variety alongside the primary footage. The main difference is that AI b-roll is created on demand from a prompt rather than shot on camera or licensed from a stock library.

Which AI model is best for generating b-roll?

Veo 3 currently produces the most cinematic results for atmospheric and establishing shots. Kling is a strong option when you need more volume at lower cost. For short-form vertical content on a platform like Leyline, both are available directly in the Videos step, where you can attach a keyframe to control composition before generating the clip.

How do I write good prompts for AI b-roll?

Specify the shot type, lighting, and mood explicitly. Keep subjects simple and avoid cramming multiple actions into one prompt. Generate several variants of each shot — the best clip is rarely the first one. Positive framing works better than describing what you don't want.

Can I use AI b-roll commercially?

Yes, in most cases. If you generate the footage yourself using a model you have commercial rights to (which covers all models on Leyline), you own the output for commercial use. Always check the specific terms of whatever generation tool you're using. For stock footage, verify the per-clip license — CC0 clips from Pexels, Pixabay, Mixkit, and Coverr are safe for commercial use without attribution.

Keep Learning

B-roll doesn't work in isolation — it connects to how you plan shots, write prompts, and choose video models. For more on building a full production workflow, read the complete AI filmmaking workflow and what is AI filmmaking for grounding on where these tools fit the broader craft. If you're choosing between models, Kling vs Veo and Seedance vs Veo 3 compare them head-to-head. For more on what b-roll is and how A-roll and B-roll differ, see what is b-roll.