Hi,
You appear to be using 512MB of allocated video memory.
The first link is definitely incorrect for your usage. Windows is including System memory that can store video memory temporarily. It's common to swap video memory into system memory when not needed even if you have a dedicated graphics card.
16MB?
That seems unlikely. Try running a Torchlight 1 or 2 demo. It won't work unless you have 512MB at least. I ran that on my dad's i5-4670K and it ran fairly well but not max settings. I can't remember if I assigned more than 512MB though. I'd run at 1600x900 res, and use FRAPS to monitor FPS. If screen tear isn't annoying then leave VSYNC OFF and aim for 40FPS.
Other:
1) GPU-Z-> http://www.techpowerup.com/gpuz/
I've never tried this on an iGPU, however I would expect you to see 512MB assigned under "Graphics card-> Memory size"
2) Update intel graphics drivers:
Go to intel site and install the tool to auto-scan your system. If it finds a new graphics driver install that.
3) In "Task Manager" you should see roughly 512MB less than your physically installed memory in some places. Probably (but not 100% sure) under "Memory-> Memory usage"; I have 8GB currently installed and show 7.9GB. If you had 8GB you might show 7.4GB.
It might however include the allocated video memory here so again, not sure. GPU-Z and running Torchlight are your best diagnostics likely.