Maybe things have changed over time, but I remember that it was always a good advise to stay away from notebooks with without dedicated memory for the graphic card in regard to video/gaming performance.
I have not found information about additional video RAM on the raspberry pi board, so it should be a kind of shared memory for cpu/gpu.
The gpu allows hardware accelerated OpenGL, but where is the memory for textures, vertices, etc. ?
Where should I search for these kind of information for raspberry pi?