Andy,
the datasheet you gave us, has contained AC characteristics. There are Figures 1,5,6,7 there which show right conditions.
For example, Figure 1 says that for refresh rate about 100Hz peak current may be DC current *2 if Pulse Width is less than 4ms.
Now, let say you have 5 LED-displays multiplexed and refreshed at 100Hz. So refresh cycle is 10ms. And as result, each display takes 2ms of refresh cycle. Now look at Figure 1 and found that with such conditions (refresh frequence =100Hz and pulse duration = 2ms) you may increase current at 3 times more than it is indicated as DC one for the part.


Regards,
Oleg