Update the freshed state

YTManager/Tasks/FetchVideos.cs

@@ -101,6 +101,9 @@ namespace YTManager.Tasks {
                 // Get all the videos which haven't been put into this channels videos.
                 var newvids = Videos.Where(nv => !channel.Videos.Any(cv => cv.YoutubeID == nv.YoutubeID));
 
+                // Say the channel has been refreshed.
+                channel.Refreshed = DateTime.Now;
+
                 // Add all the videos to the databse.
                 await db.Videos.AddRangeAsync(newvids);