According to the examples, the cv.VideoCapture() is used like this:
let cap = new cv.VideoCapture(video);
And this is the way that I was using it. I took the opencv.js file from this repo which is 13Mb, and I wanted to recompile it from the source using the functions that I need only.
did you try to literally copypaste python code ?
No, everything is vanilla JS.
Thanks for your answer!!