I highly doubt you have less than 2 gigs of vram honestly. You can check by opening task manager, click on the performance tab, find your gpu and look at where it says "dedicated gpu memory" it will show your usage out of your max.
Viewing post in BETA 0.3.2 Update [Major Polish & Bug Fixes] comments
I ran it and it runs fairly good, a bit choppy during action moments, but I don't think it's the game causing that. For some reason, the look sensitivity was stuck at 0.5, so it was difficult to move around. I did get through about 3-4 levels despite that. Couldn't find any bugs besides clipping and objects/SWAT guys stuck in floors or walls.
I do like the Half-Life inspired mechanics too, especially the gravity gun hand thing going on and the health stations. Pretty cool game overall!