Use system FFmpeg for VP9 playback on Linux

src/libs/videoDec2Decoder.cpp

@@ -92,6 +92,11 @@ public:
 	[[nodiscard]] bool Initialize() {
 		const AVCodec* decoder = avcodec_find_decoder(GetAvCodecId(m_config.codec_type));
 		if (decoder == nullptr) {
+			if (m_config.codec_type == CODEC_TYPE_VP9) {
+				Log::WriteToConsoleAndLog(
+				    "WARNING: Videodec2: The game requested VP9 video, but FFmpeg has no VP9 "
+				    "decoder. Use FFmpeg with VP9 decoding enabled.\n");
+			}
 			LOGF("Videodec2: FFmpeg decoder is unavailable for codec type %u\n",
 			     m_config.codec_type);
 			return false;