@valera-rozuvan he knows how to do that, see [video_volume_control_spec.js#L27](https://github.com/edx/edx-platform/blob/1a32508235b079b8f6b880d20eea184f469a3c9a/common/lib/xmodule/xmodule/js/spec/video/video_volume_control_spec.js#L27) =)