How do I blur part of a video?

Upload the video to Valmera and describe what to hide and when, for example "blur the whiteboard behind me from 2:05 to 2:40". The AI agent finds it in the frames, places a blur over that rectangle, renders a preview and checks that nothing shows through. You review it and export a full-resolution MP4.

Can I pixelate or black out part of a video instead?

Yes. Say "pixelate" for a mosaic or "black out" for a solid bar; blur is the default. Switching is one sentence: "make that a black bar instead." For text that must be unreadable, a black bar is the safest choice.

Does the blur follow a moving face or object?

No. Valmera has no automatic motion tracking: each censor is a fixed rectangle. For something that moves, the agent uses a larger box that covers its whole path, or several short time windows with a box for each, and checks the preview. If someone only crosses the frame for a moment, cutting that moment is often cleaner.

Can I blur only part of the video's duration?

Yes. Give a start and end ("from 0:42 to 0:55") and the censor applies only then; leave them out and it covers the whole video. Time windows follow the output timeline, so make your cuts first and add timed censors last.

Does the censor stay in place when I crop to 9:16?

Yes. Censors are applied to the original frame before any reframe, so the covered area moves with the footage when you switch to 9:16, 1:1 or 4:5. There is nothing to re-apply.

How do I hide a username or email in a screen recording?

Screen recordings are the easiest case because the text does not move. Ask "black out the email in the top-right for the whole video". If you would rather the text disappear than show a bar, ask Valmera to erase it instead; that repaints the pixels.

Is it free to blur a video in Valmera?

Creating an account and uploading are free. Editing requires a subscription. Exports are full-resolution H.264 MP4s rendered from your original file and end with a brief Valmera end card.

Blur Part of a Video: Blur, Pixelate or Black Out

To blur part of a video, upload it to Valmera and describe what to hide and when: “pixelate the email address in the top-right from 0:42 to 0:55.” The AI agent finds it in the frames, covers that rectangle with a blur, a pixelated mosaic or a solid black bar, then renders a preview and checks that nothing shows through.

Use it for anything that should stay visibly hidden: a customer name in a screen recording, a document on a desk, a house number, a license plate, a face in the background. A censor covers a fixed area of the frame for the whole video or for a time window, stays on the footage when you reframe to vertical, and comes off with one sentence.

Hide It with One Sentence

Describe what to cover, check the preview, export. Creating an account and uploading are free; editing requires a subscription.

Create an account →

See pricing →

How to Blur Part of a Video in Valmera

1
Upload the video
MP4, MOV, M4V, MKV or WebM, up to 14 GB and 3 hours. Valmera indexes it once: a word-level transcript, shot changes and frames the agent can look at.
2
Say what to hide, and when
Name the thing, the style and the span: “black out the account number in the sidebar for the whole video” or “blur the poster behind me from 1:10 to 1:40.” Leave out the style and you get a soft blur.
3
Let the agent place and check it
The agent looks at real frames, places the rectangle, renders a preview and inspects the covered moments. If anything still shows, it removes that region and places a bigger one.
4
Review and export
Scrub to the covered moments yourself and adjust in a sentence (“a little wider,” “make it a black bar”). Then export a full-resolution MP4 from Studio.

PROMPTS TO PASTE

Black out the email address in the top-right corner for the whole video.

Pixelate the license plate on the parked car from 0:12 to 0:20.

Blur the whiteboard behind me between 2:05 and 2:40.

Make that a black bar instead of a blur, and a little wider.

Blur, Pixelate or Black Out: Which to Use

All three cover the same rectangle. The difference is how much of the original survives inside it and how deliberate the result looks.

Mode	What it does	Best for
Blur	A soft Gaussian blur. Its strength scales with the size of the box up to a cap, so a very large area ends up proportionally gentler.	Background distractions, brand names, a screen behind you: things you want to fade out without drawing the eye.
Pixelate	A mosaic about eight blocks across the box’s short side. It reads instantly as deliberate censoring.	Faces and license plates in documentary or news-style footage, where viewers should see that something was hidden.
Black out	A solid black bar. Nothing of the original survives inside the box.	Text that must be unreadable: account numbers, emails, addresses, documents, anything sensitive on a screen.

One video can carry several censors, each with its own style and time window. Ask to remove one, or all of them, and the picture comes back: your original upload is never modified.

Time Windows, Cuts and Reframes

A censor either covers the whole video or runs between a start and an end time. Here is what happens to it when the edit changes later.

When you…	What happens to the censor
Reframe to 9:16, 1:1 or 4:5	The censor stays on the footage. It is applied to the original frame before the crop, so the covered area moves with the picture.
Cut anywhere (whole-video censor)	Nothing to redo. A censor without a time window covers every frame that survives the edit.
Cut or speed up footage before a timed censor	The window keeps the same output seconds, so different footage can slide under it. Make timing edits first and add timed censors last, or ask the agent to recheck.
Add b-roll, a clip or an image	Added media is not censored. Use a clean clip, or hide the detail before you upload it.

If the thing you are hiding is on screen for most of the video, a whole-video censor is the simplest and sturdiest choice. Where the frame changes a lot, several short windows, each with its own box, are more precise than one long one.

Blur It or Remove It?

A censor shows. Viewers see a blur, a mosaic or a bar and understand that something was hidden on purpose, which is what you want for a face, a plate or a document. It works on any background and at any video length.

When the goal is that nobody can tell anything was there, such as a watermark, burned-in captions, a logo or a stray object, use an erase instead. Valmera repaints those pixels from other frames and the surrounding picture. It works best on small or thin things over a steady shot. See remove an object from a video and remove burned-in text.

Limits

A censor is a fixed rectangle and does not track motion, so a face or plate that moves can slide out from under it. For moving subjects the agent uses a larger box or several time windows, and a quick crossing is often better cut. Shapes are rectangles only, with no ovals or hand-drawn masks. Added clips and images are not censored, and timed censors follow the output timeline rather than the footage. Only the picture is censored: a name said out loud needs its own cut or mute. Check the preview at the exact moments that matter before you export.

Related Workflows

For faces and license plates, including people who move and how to anonymize properly, see blur faces in a video. For screen recordings with real customer data, the product demo workflow covers the rest of the edit, from cutting dead air to zooming on clicks. Every censor option is listed in the effects docs.

Creating an account and uploading are free. Editing requires a subscription — see plans.

Using Claude, ChatGPT or Cursor? The same blur_region tool is available through Valmera's MCP server.