✳ ORIENTATION DIAGNOSE
Diagnose: video plays sideways, upside-down, or mirrored
Dynamic diagnostic state for this problem. Choose a file to run the diagnostic tree; the page rerenders with ranked causes and recommended fixes.
Direct answer
Wrong orientation comes from rotation metadata (display matrix) or a literal transform baked into the pixels. Some destinations ignore the metadata and play the pixels literally; re-export with the rotation baked in to make the file portable.
Run the diagnostic tree
The tree combines this problem's static cause ranking with the values the diagnostic engine reads from your file.