I would like to know which JavaScript stores video tag images in IE11.

It's not JavaScript, but as a way the program might do something about it.

This plug-in is scheduled to be discontinued and is still restricted, but if you are particular about IE11, you can use FlashPlayer or RealPlayer.

There is a Q&A like this.
Save Movie Files

Real Player is already installed.

>>Do you have anything to set up?

Launch IE → Tools → Internet Options → Advanced Settings →
Uncheck Enable 64-bit Processor in Enhanced Protection Mode in Security→
Similarly, uncheck Enable Enhanced Protection Mode in Security.

You can now download this video from the Flash Player video.
"The icon ""During Video Playback"" appears in the upper right corner of the video screen, so you can download it by clicking on the icon."

However, it is not 100%. Well, I can do 98% of the time.

However, the videos downloaded here can only be played on the PayPal Player, so if, for example, Windows Media
If you want to play it on Player, you need to deploy a free converter and convert it from "Flv} format to "Mpeg4".

If you would like a free converter, please contact us again as a supplement.

There is also an article about the sound.Are there some APIs that can use videos?
Generate and transfer recording and audio files in your browser

Recording in Internet Explorer 11 Web Audio API in Internet Explorer 11 Flash Player must be used because is not supported. Microphone for Flash Player There is a standard class for recording.

In addition, there are ActiveX controls, which are being removed as well as plug-ins.
I'm not sure if it supports IE11, but the feature description says ActiveX components.
BB FlashBack SDK