I don’t view the plugin. Can you enable it to check your website?
When you select the option ‘image slider’ for the background, the images are adjusted to the width of the screen, and are centered in position vertical. Therefore, the images are cut off. If you want adjust the images to the height and width screen, they will be distorted.
The script that the plugin uses, have a lot of options. You can view them in the documentation (http://bit.ly/1Aeea3e). If you want, some options can be changed.