Comments on the video:
Dave needs to be better at interpreting symbols on stamps. The airplane means it's an airmail stamp. The Swedish stamp has a butterfly symbol, and sure enough, those are closeups of butterfly wings.
THe battery charger letter mentions it can charge at 500 or 100 mA per hour. No! Ampere is already a "per time" unit. Saying x mA per hour is like saying 70 km/h, per hour.
Then there's that unused opamp on the IO board. The problem with tying both pins to ground is that the ground on the non-inverting input (with no feedback) will make the opamp want to drive the output low, while putting ground on the inverting input (again, with no feedback) will make the opamp want to drive the output high, as near the positive rail as possible. Just about any interference, including changed load or input signal on the used opamp, can make the unused opamp go into hysteresis and go from one state to the other, which can cause problems.
My recommendation would be to the non-inverting output (+) to ground, or whatever else you like, such as the same input as the other opamp, and connect the the output to the inverting output (-). Ie, connect it as a voltage follower. This should avoid any problems.