feat: Can this software sniff out YouTube videos?

### Preflight checklist

- [x] I searched [existing issues](https://github.com/ja7ad/hydra/issues?q=is%3Aissue) and this has not been proposed already.
- [x] I checked the [README](https://github.com/ja7ad/hydra/blob/main/README.md) and this is not already supported.

### Component

CLI (`hydra`)

### Problem

I hope this software can sniff out YouTube videos.

### Proposed solution

I hope this software can sniff out YouTube videos.

### Alternatives considered

_No response_

### Platforms this should cover

- [ ] Linux
- [ ] macOS
- [ ] Windows
- [ ] Android / iOS (via `libhydra`)

### Additional context

_No response_

### Compatibility

- [ ] This changes existing behavior (flags, defaults, output format, or the C ABI).

### Contribution

- [ ] I'm willing to open a pull request implementing this.

Start with the README and the hydra CLI entry point to understand existing source detection, platform support, and output behavior. Clarify the intended YouTube URL types, supported platforms, and observable success criteria before implementation; the issue does not name files or tests.

Written by the indexing model from the issue text.