Basic problem is that my laptop has been doing this screen flicker from what I can tell. I can be in the middle of something and then the screen will quickly go black for 1 to 2 seconds. What could this signal? A slow graphics card failure?
This rather sounds like the backlight is tuning off temporarily, which would mean, that the screen becomes completely dark, not only very dark grey. Check this without any ambient light. It might happen more often if you move the lid and if it is off, you should still be able to see the picture on the screen but very dim and with very low contrast. Lighting the screen with a flashlight from the side (with a low angle) will help to see a picture if it is still there. It might also happen more/less often, if you change the brightness setting.
If you can confirm this, this is either the backlight itself or a worn out inverter or cable and you should contact Toshiba as the laptop is probably still in its warranty period.
If not, this might be the graphics chip, but problems with the chip usually show different symptoms and are also likely to be seen with an attached external monitor. Intel graphics are also rather unproblematic regarding chip faults or driver issues. So I am quite sure, the backlight is the problem.