Hide subtitle when seeking back

[sdabet-orpheo]

Description

On player controller update, compare current position to start time, not only to end time, so that the current subtitle doesn't stay on screen when seeking back to an earlier position.

Type of Change

• [ ] ✨ New feature (non-breaking change which adds functionality)
• [x] 🛠️ Bug fix (non-breaking change which fixes an issue)
• [ ] ❌ Breaking change (fix or feature that would cause existing functionality to change)
• [ ] 🧹 Code refactor
• [ ] ✅ Build configuration change
• [ ] 📝 Documentation
• [ ] 🗑️ Chore