Animate the text in your terminal
Vim 26 bytes

ihello world&lt;ESC&gt;qq~gsul@qq0@q


Explanation (no .gif yet):

First, we must enter the 'hello world' text. This is pretty straightforward. It's just:

ihello world&lt;ESC&gt;


At this point, the cursor is on the 'd' in 'world'. Next:

qq              " Start recording into register 'q'
  ~             " Swap the case of the character underneath the cursor, and move the cursor to the right
   gs           " Sleep for one second
     u          " Undo the last change (of swapping case).
      l         " Move one character to the right (Get it? 'l' == 'Right' because vim is intuitive!)
                " This will cause the error to break on the last character of the input.
       @q       " Call register 'q'
         q      " Stop recording
          0     " Move to the first character
           @q   " Call the recursive macro


There are also two other 26 byte versions I found:

ihello world&lt;ESC&gt;qq~gsulq011@q
ihello world&lt;ESC&gt;011@='~gsul'&lt;cr&gt;