Is there a way to check the size of the video memory? Specifically, is there one that works accurately for both integrated GPU's as well as PCI/AGP graphics cards?
Many integrated GPU's have dynamically allocated memory, so the solution would hopefully return either the maximum available video memory or the currently allocated amount. For stand-alone NVidia or ATI cards it would obviously return the total amount of physical GPU RAM.
lspci -v does output memory figures, but I do not believe it is the video memory. I suspect the figure reported is some system memory allocation or block or channel size, but I don't know for sure. You can see in these test results that lspci was wrong in 5 of the 6 tests.