Some sites throttle requests, but throttling can be avoided with many small range requests. yt-dlp implements a "http_chunk_size" key in its -J output to inform us of the ideal size. https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/21703 has just been merged, which allows use the http_chunk_size to greatly speed up how fast YouTube videos get loaded into the cache by mpv. Should the FFmpeg that mpv is built against lack the request_size AVOption, then this will silently not do anything new, so no version checks are needed. Specifying multiple_requests=1 like suggested in https://github.com/mpv-player/mpv/issues/8655#issuecomment-3872689494 does not seem necessary. Fixes #8655. Supersedes #15612. Co-authored-by: Nicolas F <[email protected]>