YouTube's embed API requires knowing the embedding origin to authorize
playback. The referrerPolicy="no-referrer" was stripping the Referer
header, and the missing origin param meant youtube-nocookie.com couldn't
verify the embed source, causing Error 153 (video player configuration
error). Fix: pass origin param explicitly and let the browser send the
default referrer.
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