Please enter ipython --pylab command and enter in the ipython shell and then use the above command. Question mark works with ipython terminal and not the python shell. If you are in python shell then type help(round).
You seem to be using the simple python insterpreter or IDLE environment
Please follow the instructions in the video EXACTLY as specified.
Open an IPython console by opening a terminal followed by the command :
Then the python functions and commands shown in the video will work as expected