fix(playback): structure Video.js diagnostics

.changes/playback-structured-videojs-diagnostics.md

@@ -0,0 +1,9 @@
+---
+type: fix
+area: playback
+---
+
+The default web player now reports safer, more accurate streaming errors:
+confirmed network and encrypted-segment failures keep structured details,
+while ambiguous Video.js errors remain unknown instead of suggesting the
+wrong cause.