tweak streaming engine editor

ErsatzTV/ViewModels/ChannelEditViewModel.cs

@@ -31,7 +31,19 @@ public class ChannelEditViewModel
         set => PlayoutOffset = new TimeSpan(hours: value, minutes: 0, seconds: 0);
     }
 
-    public StreamingEngine StreamingEngine { get; set; }
+    public StreamingEngine StreamingEngine
+    {
+        get;
+        set
+        {
+            field = value;
+            if (value is StreamingEngine.Next)
+            {
+                StreamingMode = StreamingMode.HttpLiveStreamingSegmenter;
+            }
+        }
+    }
+
     public StreamingMode StreamingMode { get; set; }
     public int? WatermarkId { get; set; }
     public int? FallbackFillerId { get; set; }