The rifle seen in the video of Julius Malema at an EFF rally is not an AK-47 but rather an AR-15 or a generic directive thereof.
Secondly, it's clear in the video that the rifle used is not a full automatic but a semi-automatic. This specific weapon is legal for security companies to use and own in South Africa.
It's difficult to tell if Malema is shooting live or blank rounds, however it is definitely a real firearm being used. Coming from experience having served in the French Foreign Legion, I can assure you that is a real firearm used by Malema.