The PSP (2004) has no web browser capable of modern streaming sites, no app store, and no direct video download function. You must transfer files from a computer.
Connect PSP to PC via USB (Settings → USB Connection) or remove Memory Stick and use a card reader.
M4Vxxxxx.MP4 (e.g., M4V00001.MP4)MP_ROOT/100MNV01/ on Memory Stickyt-dlp -f "bv*[height<=272]+ba/b[height<=272]" --merge-output-format mp4).M4V#####.MP4 (sequential numbers).MP_ROOT/100MNV01/ on Memory Stick.Legal: Only transfer content you own or have rights to. Downloading copyrighted video without permission is illegal.