PreferenceSpecifiers Type PSToggleSwitchSpecifier Title Enable video Key enable_video_preference DefaultValue Type PSToggleSwitchSpecifier Title Automatically start video Key start_video_preference DefaultValue Title Codecs Type PSGroupSpecifier DefaultValue Key mp4v-es_preference Title mpeg4 Type PSToggleSwitchSpecifier DefaultValue Key h264_preference Title h264 Type PSToggleSwitchSpecifier DefaultValue Key vp8_preference Title VP8 Type PSToggleSwitchSpecifier