Screenshot needs to be updated

In testing the Video Solution pack for 7x.1.8, I noticed that both the github and wiki pages for the this SP have out-of-date screenprints of the config page.

The screenprint (filename: "/islandora_video_config.png"), should perhaps be replaced with an updated one for two reasons.

1. The default value shown for the "MP4 audio codec" is "aac" but the instructions say the default is "libacc".

2. The following checkbox option is missing from the screenprint:

"Play OBJ datastream if MP4 is not present"
"Check this box to use the OBJ datastream in the viewer (configured above) if the MP4 datastream is not present and the OBJ datastream has mimetype video/mp4."