If none of the extractors successfully sniff the content then we will fall back
to inferred file types in the following order:
- Webvtt if the media comes from a SUBTITLE EXT-X-MEDIA.
- The type of media declared in the HTTP "Content-Type" header.
- The type of the media according to the file extension.
- Transport stream.
Issue: #8700
PiperOrigin-RevId: 362519769
