The PSP only plays specific video formats. You must convert first, then transfer via USB.
ffmpeg -i input.mkv -vf "scale=480:272" -c:v libx264 -profile:v main -level 3.0 -b:v 1500k -c:a aac -b:a 128k output.mp4PSP folder → VIDEO folder (create if missing)..mp4 files here. Filenames: no special chars, ≤64 chars.