Add new video player page with responsive layout, video details display, and comments section. Includes video player, channel info, like/dislike buttons, and interactive elements. Also add null checks in main script to prevent errors when elements are missing.
- Add new video.html page with YouTube-like interface
- Change default language from zh-CN to en-US in index.html
- Remove deprecated media.json file
- Update Chinese comments to English in index.html
