I'm pretty sure it's intended to make people be more aware of their energy consumption in the long term, I wasn't aware anyone was suggesting switching off for an hour has any actual effects.
If that is what they intended then I doubt it will work, it probably is their intention but it won't convince people to do it in the long run. People will turn off lights and electric devices when not using them (like me) if they really care about the planet, other people who don't care as much but still take part in earth day will probably just turn off electronics for an hour and then think "Well I've done my part, I feel good, now I won't even think about doing it again until next earth day." 1 hour isn't going to change many peoples minds.