Improve web video extraction support for modern streaming sites #58

Description

Castor currently struggles with some modern streaming websites that use
adaptive streaming and dynamic video players.

Observed behavior

DASH streams with separate audio/video tracks

Some websites provide video and audio as separate DASH representations
(for example, fragmented MP4 .m4s streams).

Castor may capture only one representation instead of the complete media
stream.

Result:

• audio playback works;
• video playback fails or shows a blank screen.

The browser can play these videos normally because it combines the audio
and video representations internally.

YouTube playback extraction

YouTube pages do not appear to expose a directly usable video stream
through the current extraction process.

Castor may fail to detect any usable stream and only capture unrelated
page assets instead of the actual media stream.

Expected behavior

Improve web video extraction support for modern streaming platforms:

• detect DASH manifests and stream metadata;
• combine separate audio/video representations when required;
• better handle dynamic video players such as YouTube;
• extract a complete playable stream for casting.

Environment

• macOS
• Castor latest version
• ffmpeg 8.x
• DLNA renderer: Kodi