Play "source:blob" live online video with Processing

Hi! I’m trying to play live traffic webcam online video in order to analize it in real time with processing and opencv.
The main problem I found is getting access to the video itself, while street web sources go changing each minutes and are managed through a blob node in the DOM.
I found this three years old thread very clarifying, but only until a certain point:
The .m3u8 video that is used by this page is only available from the “network” tab and I don’t realize how to inspect it with processing.
In other pages, where the source is not .m3u8 but .mp4 the problem remains there: the video itself is not in the DOM, so loadStrings(“url”) doesn’t seem to work.
Maybe I’m getting confused in some basic point and I can get the url of the video through loadstrings() and a regex search, but while the real video source is not there, I cannot imagine how to do it.
Any simple clue would be very greatly welcome. Thanks a lot.