Why is there missing files such as bgs_demo.vcxproj after I follow the video steps?

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**Describe the bug**
Why is there missing files such as bgs_demo.vcxproj after I follow the video steps?

**To Reproduce**

**Expected behavior**
I hope to get the complete file after following the video steps

**Screenshots**
If applicable, add screenshots to help explain your problem.

### System information
**Desktop (please complete the following information):**
- **OS Platform and Distribution (e.g., Linux Ubuntu 16.04)**:
- **Python version (for issues related to the python wrapper)**:
- **Java version (for issues related to the java wrapper)**:
- **MATLAB version (for issues related to the matlab wrapper)**:
win10, python is 3.7.0, OpenCV is 3.4，Visual Studio 2019
**Additional context**
Add any other context about the problem here.