Your wiring cannot be verified without a picture that shows both ends of every wire and the code that goes with the picture.
Do you realize that the horizontal power buses have a gap in the middle?
Your video cannot be adequately interpreted without seeing the code that was used to generate the display.
If you look at the first part of the video, while you are properly displaying the initial characters, you can see faint 'blocks' on both rows of your display. After you try to display the 'o', while you are displaying the garbage characters, you will notice that you can no longer see blocks in the second row. This implies that the configuration of the LCD controller has changed and that it is no longer properly set up to send information to a two-row display. You didn't let either garbage display run long enough to fill up all 80 memory locations so I can't speculate any further.
What happens if you start displaying letters at a different point in the alphabet? Does it foul up at 'o', at the 15th character, or somewhere else?
Have you tried any other libraries?
Have you tried using some other location on your breadboard?
Don