Can this program play DVD video files?
Yes, KMPlayer is able to play DVDs from discs or from DVD local folders. To do this, simply open the application then right click inside the window and select Open > Drive or Open > Open Folder.
Yes, of course.
But Blu-ray is different with DVD which can't be played with it. In order to watch this kind of movies, you have to prepare another Blu-ray player and a Blu-ray drive. But VLC can't do this, you should know that.
This might help you