graph TD A[Read download_log.json] --> B[Process Videos Loop] B --> C{For Each MP4 Path} C --> D[Extract Thumbnail Images] D --> E[Save First Thumbnail] E --> F[Check File Status] F --> G[OK Status] & H[Error Status] G --> I[Store Result] H --> I I --> J{More Videos?} J -->|Yes| C J -->|No| K[Collect All Results] K --> L[Format Report Data] L --> M[Generate Integrity Report] M --> N[Save integrity_report.txt] N --> O[End Process]