MediaCapture: Default to H264 on all platforms

H264 is provided by OpenH264 on Linux.

src/util/media_capture.cpp

@@ -2234,15 +2234,8 @@ bool MediaCaptureFFmpeg::InternalBeginCapture(float fps, float aspect, u32 sampl
       }
     }
 
-    // Default to VP9, because there's no LGPL H.264 encoder.
-    // Except on MacOS, where we get it through VideoToolbox.
-#ifndef __APPLE__
-    constexpr AVCodecID default_video_codec = AV_CODEC_ID_VP9;
-#else
-    constexpr AVCodecID default_video_codec = AV_CODEC_ID_H264;
-#endif
-
     // Use container default if available.
+    constexpr AVCodecID default_video_codec = AV_CODEC_ID_H264;
     if (!vcodec && wrap_avformat_query_codec(output_format, default_video_codec, FF_COMPLIANCE_NORMAL))
       vcodec = wrap_avcodec_find_encoder(default_video_codec);
     if (!vcodec)