graph TD A[Start Subagent 5: Combine Avatar Angles] --> B[Verify Input: 4 MP4 URLs] B --> C{Check MP4 Format} C -->|Not 9:16| D[Format Conversion] C -->|Is 9:16| E[Prepare for Concatenation] D --> E E --> F[Call Skill #173: Concatena Videos] F --> G[Input 4 MP4 URLs in Order] G --> H[Process Concatenation] H --> I[Generate Combined MP4] I --> J[Verify Output Length] J -->|Not ~40s| K[Length Adjustment] J -->|Is ~40s| L[Save Final MP4] K --> L L --> M[Output combined-newsreader-angles] M --> N[End Subagent 5]