My screen broke (several cracks, turning the tablet on just gives me a pixelated looking screen) on my Acer Iconia One tablet, and I can't login or enable MTP file transfer, or USB debugging, etc. Any way I can still retrieve my pictures and video off the tablet?
On your own, not likely. You need to be able to access the display to tap whatever it requires. You would have to replace the display.
You can try taking it to a local tech and see if they have another means to transfer the files, and what it would cost to do so, or if they can only do it after a display replacement. Depending on the cost, it may be worth replacing the display if the info on the device is important to you.