WebM vs. MP4
WebM is an open video format from Google, used by websites, screen recorders and browser-based tools. It works well in browsers, but many devices and programs – older iPhones, some video editors, presentation software and messengers – handle MP4 much better. MP4 is the standard for sharing, editing and uploading.
What changes
The video is re-encoded from VP8/VP9 or AV1 into an MP4-compatible codec, and the audio is converted as well. Quality stays very close to the original. Screen recordings with lots of motion or high resolution may take a while to convert on slower devices, since all processing happens locally.
How to convert
Drop the WebM above, MP4 is preselected, click “Convert” and download. FFmpeg runs in your browser – the video is never uploaded.