Hello Mike,
I believe the section that you are interested in is after 44:00 minutes in the video that you mentioned. I noticed that the section does not show how the ladder functions, so I will detail that below:
In one net, link a Positive Transition contact to the Up button
To the right of the contact, place an Increment function block, and link that to the List of Text by Pointer Memory Integer
This will cause the value of the Image index to increase by one every time the Up button is pushed.
In the next net, place a "Greater than or equal to" compare block, and link the variables as follows: Variable A = Memory Integer linked to the List of Text Index; Variable B = some constant the constant = the number of text variables
To the right of that block, place a "Store" function block, and link the variables as follows: Variable A = 0; Variable B = Memory Integer linked to the List of Text Index.
This will constantly compare the value of the index, and when it reaches the constant put in the compare block, it will reset it to 0. For instance, if you have 3 different texts to display, you would have a value of 3 in the compare block. When the index reaches the value of 3, it will reset to 0. This is because those 3 text variables would be linked to Index values of 0, 1, and 2 respectively.
Hope this helps!
Will