Add a generic video player widget.

OpenRA.Game/Graphics/VideoLoader.cs

@@ -0,0 +1,32 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
+ * This file is part of OpenRA, which is free software. It is made
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version. For more
+ * information, see COPYING.
+ */
+#endregion
+
+using System.IO;
+
+namespace OpenRA.Video
+{
+	public interface IVideoLoader
+	{
+		bool TryParseVideo(Stream s, out IVideo video);
+	}
+
+	public static class VideoLoader
+	{
+		public static IVideo GetVideo(Stream stream, IVideoLoader[] loaders)
+		{
+			foreach (var loader in loaders)
+				if (loader.TryParseVideo(stream, out var video))
+					return video;
+
+			return null;
+		}
+	}
+}