How to use a clip from your own social post as b-roll

Last updated 2026-09-22 · 8 min read

What is the short version?

You already filmed the thing you need as b-roll, and you posted it months ago. Reusing it now means getting the file back out again and dealing with everything the platform baked into the picture on the way through.

1. Give Vizard Agent the post's link and the main video.
2. Say which line or section the b-roll illustrates.
3. Expect crop tests, because the clip has captions in it.

What do you need before you start?

The link and the main edit it belongs in. Vizard Agent fetches the published clip itself, and it needs your main video as well, both to know what the b-roll is covering and to measure where that video's own captions sit.

• The post link. Yours, or one you have the rights to use.
• The main video. The edit the b-roll goes into.
• What it illustrates. The line it should sit under.
• Which shots. If only part of the post is useful.
• The frame. The shape your edit is in.

What do you type into Vizard Agent?

Say what the clip is for, not just where it came from. "Use this as b-roll for this video" tells Vizard Agent that the clip is illustration rather than content, which is what licenses it to crop into the picture and drop the clip's own audio.

Prompt

Variants worth knowing:

• "Use it as b-roll." Illustration, not a second subject.
• "So none of its own captions show." The real constraint.
• "Keep my main video's captions." The layout that wins.

What does Vizard Agent actually do?

Here is the Vizard Agent sequence on an interview that needed b-roll pulled from two already-published reels. Almost all of the work turns out to be geometry: what each clip has burnt into it, and where it can safely be cropped.

1. Checks the uploaded video and downloads the linked reel.
2. Reads the transcript and downloads the second reel.
3. Restores both reels and samples frames from all three videos.
4. Views frames from the main interview and from each reel.
5. Checks caption placement and finds the shot changes inside the reels.
6. Compares full frames from the main video and both reels.
7. Inspects the main video's caption band across time.
8. Measures the exact caption box and the panel split positions.
9. Previews how each reel looks cropped to the top panel.
10. Tests a lower crop window on the planting shots.
11. Measures the caption box geometry and checks whether the captions animate.
12. Generates a caption mask track from the main video.
13. Test-renders the first twenty seconds to check the timing and the composite.

Step eight is the step that makes the layout work. A reused clip has to fit into whatever space your edit leaves, and that space is defined by where your captions sit — which is a measurement rather than an impression.

Step ten is where reused footage usually fails. The obvious crop keeps the middle of the frame and the platform's captions live there; a lower window keeps the hands and the plants and loses the text.

Step eleven matters because captions move. A caption box that grows as words appear needs a mask that follows it, not a rectangle measured on one frame.

What does the result look like?

Your edit with real footage of the thing being described, cropped by Vizard Agent so that neither set of captions collides, the main video's audio running throughout, and no sign at all that the b-roll came from somewhere it had already been published.

When does this not work well?

Some posts cannot be reused at all. A clip with a platform watermark burnt into it, one carrying music you do not have the rights to, or one whose captions cover the subject leaves Vizard Agent with nothing usable once the cropping is done.

• Platform watermarks. They move around the frame.
• Licensed music in the clip. Its audio cannot travel.
• Captions over the subject. Cropping them out loses the shot.
• Very low resolution. Cropping in makes it worse.
• Somebody else's post. You need their permission.

How do you fix a result that came back wrong?

Say what is visible in the frame that should not be. Vizard Agent moves the crop window or masks the offending area rather than replacing the clip outright, and in practice moving the crop is the adjustment that solves most of these complaints.

• "Their caption is showing." The crop window is moved down or tightened.
• "You cropped her out." A different window is tested on those shots.
• "The b-roll is too long." It is trimmed to the line it illustrates.
• "The audio changed." The main video's track is restored throughout.

How does Vizard Agent compare to doing it yourself?

By hand you download the post, drop it on the timeline, and discover the captions. Then you scale it up to push them off frame, and now the b-roll is soft and does not match the rest of the video.

Common questions

Can it fetch any post? Public ones, and Vizard Agent will say when a link cannot be reached.

Should I use someone else's clip? Only with permission — the footage belongs to whoever filmed it.

Will the b-roll keep its sound? Not usually. Vizard Agent keeps your main audio and drops theirs.

Can it use several posts? Yes. Vizard Agent treats each one as its own source and crops it accordingly.

What if the clip is vertical and my video is not? Vizard Agent crops or frames it, and will tell you what that costs.

Can it remove the burnt-in captions instead? Sometimes, though cropping is cleaner when the layout allows.

Will the quality match? Rarely exactly — Vizard Agent can grade it closer to your main footage.

Can it find the right moment in the post? Yes. Vizard Agent maps the shots inside the reel before choosing.

How long should a b-roll insert be? As long as the line it covers, which Vizard Agent times to the transcript.

Can it repost my own footage safely? Your own footage, yes. Vizard Agent flags anything else it finds in the frame.

What about the platform's own watermark? That is usually the reason a clip cannot be reused.

Can I supply the original file instead? Yes, and it is always better than the published version.

Does it change my main video? Only where the b-roll sits over it.

How do I check it? Look at the corners of the inserted shots; that is where borrowed captions survive.