As the manual entry for --hwdec states that d3d11va and d3d11va-copy require Windows, it can be assumed that it also works for Windows 7. Since it doesn't, according to https://github.com/mpv-player/mpv/issues/3285#issuecomment-228593539, and personal testing, updating the manual accordingly and making the hwdec OS requirements for ANGLE in line with videotoolbox, where OS version is stated.