I do not have the time right now, to look into the example, but I tried this yersterday at my testing.
I have attached a picture of the modifications I made to the SOPC-system. I added a FrameBuffer, which I configured to use the same read burst and master bit width to access the DDR SDRAM in the design as your FrameReader. As I run this system on the neek it worked quite fine and gave me the testpattern. I had also configured the FrameBuffer to not add or throw away frames, so normally if the stream would have run out of the specification I expected the LCD image to be altered, too.
I am curious what you get out of the project when you carry over the design from the example you found.