When checking for a correct version of x11-libs/libva, the mpv's build system verifies whether a new enough version of the VA-API spec is supported by whatever version of libva, but the ebuild uses the VA-API version when specifying a dep on libva. These two versions are not tied together. Here's how to translate among these two: http://cgit.freedesktop.org/vaapi/libva/log/configure.ac
commit da89c98fd8b66cf7c8f591913be62f64ed710488 Author: Ilya Tumaykin <itumaykin@gmail.com> Date: Tue Dec 22 18:42:20 2015 +0300 media-video/mpv: fix libva dependency version wrt bug 565618 This was originally submitted by Vindex17 in PR #318. Gentoo-Bug: 565618 Package-Manager: portage-2.2.24 This fix is included in 0.11.0-r1, 0.14.0, 9999.