Look at the picture

Please explain in detail how this is happening. What were you doing at the time? surfing, watching a clip, reading something . . . .

What website does this happen on?

Web search: OpenH264 is a free software library for real-time encoding and decoding video streams in the H.264/MPEG-4 AVC format. It is released under the terms of the Simplified BSD License.

I think it should be this I modified the default download tool As a result, Firefox's built-in download tool is not used

The official website has an introduction https://support.mozilla.org/en-US/kb/open-h264-plugin-firefox

This plugin is only used for WebRTC, so if you do not use WebRTC then you can ignore this message about downloading the OpenH264 plugin.

• https://en.wikipedia.org/wiki/WebRTC

Well, I resume the browser download, the plug-in has been automatically updated, and the skills of the technical staff need to be improved