I want to build a RTSPMediaFactory with GStreamer that would redirect the client to a video or another based on how many clients arrived before:
First two clients should be redirected to video/stream 0. Next ones should be redirected to video/stream 1.
Here’s what I have come up so far:

import gi
gi.require_version('Gst', '1.0')
gi.require_version('GstRtspServer', '1.0')
from gi.repository import Gst, GstRtspServer, GObject

class DynamicRTSPMediaFactory(GstRtspServer.RTSPMediaFactory):
    def __init__(self, video_files):
        super().__init__()
        self.video_files = video_files
        self.client_count = 0
        self.set_shared(True)

    def do_create_element(self, url):
        self.client_count += 1
        if self.client_count <= 2:
            video_file = self.video_files[0]
        else:
            video_file = self.video_files[1]

        pipeline_str = f"filesrc location={video_file} ! decodebin ! x264enc ! rtph264pay name=pay0"
        return Gst.parse_launch(pipeline_str)


class RTSPServer:
    def __init__(self):
        Gst.init(None)
        self.server = GstRtspServer.RTSPServer.new()
        self.server.props.service = "8554"  # set the port
        self.mount_points = self.server.get_mount_points()
        
        # Create and set up the dynamic factory
        video_files = ["test.mp4", "test2.mp4"]
        self.factory = DynamicRTSPMediaFactory(video_files)
        
        # Add the factory to the mount points
        self.mount_points.add_factory("/test", self.factory)
        
        # Attach the server to the default main context
        self.server.attach(None)

if __name__ == "__main__":
    server = RTSPServer()
    GObject.MainLoop().run()

The issue is that all clients receive the video/stream 0. client_count isn’t incremented at each new connection. Is this the right approach ?
If it is of any use, I use VLC to test the RTSP Server.