I used the 50000 as the backend port and 9100 as the front port and it works properly on my side. Have you referred to the source code I attached https://github.com/NVIDIA-AI-Blueprints/video-search-and-summarization/blob/main/deploy/docker/local_deployment_single_gpu/.env#L8?
You can also use the sudo netstat -tulpn command to check the port that have already been used on your device first.
Can you successfully deploy using our default configuration?
FRONTEND_PORT=9100
BACKEND_PORT=8100
You can also refer to our FAQ Network Ports first.