I don't specifically know the answer to your first question if the VRAM is not DRAM (shared memory), but certainly rebooting will not simply automatically clear out DRAM.
The problem is that most people won't even click the "Register" link. For me personally it has nothing to do with email though. It's an obstacle which I can't be bothered with, even if it's just username and password.
The advantage of making you register is tracking your progress (and analytics, for the benefit of the webmaster). I suppose it could give you the option to just set a cookie, but that has the disadvantage of being device-specific. Also, some browser crashes can wipe out recently set cookies.
It is working fine for me. I wanted to know how the application works. I mean there should be HTTP requests going to the server, but I don't find any. The same is the case with the other browser where I am viewing the code.