Use logical OR when merging fetched metadata so null values from
failed og: extraction don't destroy valid defaults (e.g. YouTube
thumbnail set before the fetch).
YouTube may block og:image extraction via BackspaceBot user-agent.
Use img.youtube.com/vi/{ID}/hqdefault.jpg as a guaranteed thumbnail
that doesn't require metadata fetching. If og:image is successfully
fetched, it overwrites the fallback.
1. Video aspect ratio: remove container border/overflow-hidden, use
preload="metadata" so browser knows dimensions before play
2. YouTube Error 153: remove sandbox attr (too restrictive), add full
allow permissions (encrypted-media, accelerometer, gyroscope, etc.)
3. Google Images not displaying: detect image Content-Type from HTTP
response in metadataFetcher, override classifier to create image
embed for URLs that serve image/* content
4. Audio seeking broken: add HTTP Range request support in uploads
route (Accept-Ranges, Content-Range, 206 Partial Content)
Jannis Braun