Step 1: Project Setup

1. Create a new Node.js project folder.
2. Initialize the project using npm init and follow the prompts.
3. Install the required packages: express, mongoose, and any other necessary packages using npm install.

Step 2: Create the Express Server

1. Create an index.js file as the entry point of your application.
2. Import express and set up the server.
3. Define your middleware, such as parsing JSON and handling CORS.

Step 3: Define and Implement API Routes

1. Create a routes folder to organize your route handlers.
2. Inside the routes folder, create a file for each API version (e.g., v1Routes.js).
3. Define route handlers for each of the specified endpoints (GET /v1/videos, GET /v1/videos/:videoId, POST /v1/videos, PATCH /v1/videos/:videoId/votes, PATCH /v1/videos/:videoId/views).

Step 4: Set Up MongoDB

1. Create a models folder to store your data models.
2. Define a Mongoose schema for your video data, including fields like title, genres, content rating, upload date, and view count.
3. Create a Mongoose model based on the schema.

Step 5: Implement API Logic and MongoDB Integration

1. Inside the route handlers, implement the logic to interact with the MongoDB database using Mongoose methods.
2. For GET endpoints, retrieve data from the database and respond with the appropriate JSON.
3. For POST and PATCH endpoints, process incoming data, perform necessary updates or inserts in the database, and respond with the appropriate JSON.

Step 6: Improve GET /v1/videos Endpoint

1. Enhance the GET /v1/videos endpoint to support query parameters for video title search, genre filtering, and content rating filtering.
2. Implement sorting based on video upload date or view count, as specified.

Step 7: Connect Backend to Frontend

1. Integrate your backend API routes with the XFlix frontend application.
2. Update frontend API calls to use the appropriate backend endpoints.

Step 8: Test with Postman

1. Use Postman to test your APIs individually.
2. Test various scenarios, including creating videos, updating votes and views, filtering, and sorting.

Step 9: Create GitHub Repository and README

1. Create a GitHub repository for your project.
2. Add your project files to the repository.
3. Create a README.md file that explains the project, provides API documentation, includes instructions for setting up the project locally, and outlines how to deploy the full-stack application.

Step 10: Deploy Full-Stack Application

1. Choose a hosting platform for both the backend and frontend (e.g., Heroku for backend, Netlify/Vercel for frontend).
2. Follow the deployment guides for each platform to deploy your full-stack application.

Remember, this is a high-level overview, and each step involves detailed implementation. Make sure to consult the official documentation for Node.js, Express.js, MongoDB, and any other libraries you use, for in-depth instructions on implementation details. Additionally, adapt and customize the steps according to your project's specific requirements.