Capture a Video Stream from a site and save it locally

I have a streaming link to a camera that streams in mjpg format. I want to capture a limited stream from the site, save that locally to a file, covert the video to an appropriate format, and then send it onwards using a Chatbot API.

I've been looking around and found quite a few posts on creating a video chat app, or embedding a player your web app, but not that much on accessing a streaming site and storing a snippet from there locally. Does anyone know how one could do this?