Prevent stream player from seeking on streams

This could cause issues on HLS streams in some cases see #55

Author: MerlinVR

Assets/USharpVideo/Scripts/USharpVideoPlayer.cs

@@ -277,8 +277,11 @@ public override void OnVideoStart()
 #else
                 _videoStartNetworkTime = GetNetworkTime() - _videoTargetStartTime;
 #endif
-
-                _videoPlayerManager.SetTime(_videoTargetStartTime);
+    
+                if (IsInVideoMode())
+                {
+                    _videoPlayerManager.SetTime(_videoTargetStartTime);
+                }
 
                 _ownerPlaying = true;