How to read multi-camera streams with OpenCV seamlessly?

Question

I went through this beautifully explained Q/A and I want something similar into a much stripped down version of the code I found there which includes PyQt4 and qdarkstyle.

My code is as follows:

import pafy
import base64
import zmq
from threading import Thread
import cv2
import time


class IPCamera(object):
    def __init__(self, src=0):
        self.frame = None
        self.status = None
        self.capture = cv2.VideoCapture(src)
        self.capture.set(cv2.CAP_PROP_BUFFERSIZE, 2)
        self.FPS = 1/25
        self.FPS_MS = int(self.FPS * 1000)

        # Start frame retrieval thread
        self.thread = Thread(target=self.update, args=())
        self.thread.daemon = True
        self.thread.start()

    def update(self):
        while True:
            if self.capture.isOpened():
                (self.status, self.frame) = self.capture.read()
                # self.frame = cv2.resize(self.frame, (640, 480))  # resize the frame
            time.sleep(self.FPS)

    def show_frame(self):
        cv2.imshow('frame', self.frame)
        cv2.waitKey(self.FPS_MS)


if __name__ == '__main__':

    # Sample youtube video starts
    youtube_link = 'https://www.youtube.com/watch?v=QgaUKlAuqn8'
    vPafy = pafy.new(youtube_link)
    play = vPafy.getbest(preftype="mp4")
    src = play.url
    # Sample youtube video ends

    # Creating ZMQ context starts
    context = zmq.Context()
    footage_socket = context.socket(zmq.PUB)
    footage_socket.connect('tcp://localhost:5555')
    # cv2.namedWindow("Client Started!")
    # Creating ZMQ context ends

    threaded_camera = IPCamera(src)
    while threaded_camera.capture.isOpened():
        try:
            if threaded_camera.status is True:
                encoded, buffer = cv2.imencode('.jpg', threaded_camera.frame)
                jpg_as_text = base64.b64encode(buffer)
                footage_socket.send(jpg_as_text)
                # key = cv2.waitKey(1)
                # threaded_camera.show_frame()
                # if key == 27:  # exit on ESC
                #     break
            # else:
            #     break
        except AttributeError:
            pass

The above code is running fine, I want to implement the code from the Q/A on the aforementioned link with those libraries removed. Can you help me in that?