How to get video fragment in HTML?

Question

JavaScript

I would like to process video in HTML5. The bottom line is that we have two players. One of them plays a video. The user clicks on stop. Relative to its position, a small piece of video is cut out (about 5 seconds). And this little piece can be reproduced, its borders can be edited, and ultimately saved.
Is it possible to do this on the web? Made in Java/Swing/VLCj, but everything is terribly crooked...