I understand you have some question regarding video memory on your computer.
I am sorry, I was not able to see screen shots you have sent.
The graphics controller on your system handles up to 1.7GB of video memory; this is called Dynamic video memory. This video memory capacity depends on the motherboard maker or computer manufacturer, I recommend checking the link below for more information:
I have checked a list of games that were tested using your graphics controller and Assassins Creed 3 is playable.