Is the black area part of the result?
A valid transparent result carries alpha data and can be reviewed against multiple surfaces.
AlphaPublish
Create a Transparent WebM without building a video pipeline.
Turn a short source clip into a WebM with an alpha channel, review it against multiple surfaces, then download it or publish it for the web.
Why WebM with alpha
Use transparent motion for website heroes, presenters, products, mascots, and decorative page layers.
Why a file is not the whole workflow
A file still needs hosting, caching, autoplay handling, browser tests, and a safe failure state.
Download or host
Download Transparent WebM or serve versioned media through a stable hosted asset.
Frequently asked questions
What happens when motion cannot play?
The hosted player keeps a verified poster visible.