attempting to use the display for a dual purpose is going to be a real nightmare ... especially how do you plan to get good resolution and response time on the array, while still having it display data ... a high response time is going to make the array appear solid on, as seen in the NYU videos
as far as having parts of your led matrix appear dim, that is a driving problem... here are my thoughts
the easiest example setup would be like this... your array is N columns by 8 rows (the number of columns isn't important). for the columns, you use ULN2803 (or something like that) darlington current sink drivers... they're good to 500mA per column.
for the rows, you use PNP darlington array or P type transistors (fet or bjt).
you load up all your column data (serial shift registers work best to control the darlington drivers), and then scan your rows 1...8 to keep the current demands on your power supply low.
with this setup, you should be able to build an led sign as big as you want, without overloading your controller.
of course, this doesn't help for touch sensing. as far as I can tell, the two tasks are mutually exclusive.
you might want to look into another application, using leds and sensors, called internally frustrated reflection. you shine tighly focused leds through a plane (like a piece of plexiglas), with detectors opposite the emitters. foreign objects contacting the plane will cause some of the light to escape the plane, registering a change in the detectors. so a clear sheet of plexiglas covering your led matrix would allow you to touch sense, without having to figure out how to multitask the display.
another possiblity may be to use a common cathode bicolor matrix. your data would be displayed using the green diodes, and the touch sensing would be performed using the red diodes... the visual result should be yellow lettering on a red background