Regarding the FAQ for Coriolis Effect, it only addresses a small portion of it.
Q: "How come when I flush my toilet in the northern hemisphere it goes counterclockwise but I have this friend in Australia and when he flushes it goes clockwise?"
A: You are mistaken. The Coriolis effect adds at most one (counter)clockwise rotation per day, and fewer as you get closer to the equator. The water in your toilet spins much faster than that (at least once per minute, or 1440 times per day), so the additional or lost rotation from the Coriolis effect would not be noticed.
So with that statement, I am concluding you DO believe in the Coriolis effect, only it's very weak. But, lets be serious here. Given that toilets are on a very small scale, designs and other various things can easily overcome the effect. Look on a much grander scale. Take cyclones for example. They spin counter clockwise in the Northern, and clockwise in the Southern. This does not have to do with the fact that you get turned 180 degrees when you move across the Equator. If you were to theoretically jump out of an airplane over a cyclone in the Northern, and then again over one in the Southern and stay there for a day; you would see clearly they rotate oppositely. What is clearly making a cyclone in the Southern hemisphere rotate clockwise? (More on this in the videos).
As I said earlier, that is only a small portion of the Coriolis effect. What about trajectories over long distances? Take for example a sniper, who shoots at his target +1 mile away in the Northern hemisphere. His crosshairs are between the eyes - with no calibrations to his scope, he will hit his target below and to the right. We understand the below part here, be it gravity or UA as some of you believe here. What about the right part? Now lets adjust that scope. You aim high for gravity, then you aim a little bit left to account for the wind. You fire again...and the bullet STILL misses to the right. Why is the bullet missing!?! It's because of the Coriolis effect. Objects in the Northern hemisphere are deflected right as viewed from the original movement (vice verse in the Southern).
When have a trajectory traveling long distances, you have to take into account of the rotation of the Earth! If you are in the military, specifically artillery or a sniper, you HAVE to learn about this (granted computers do the math now, you still have to manually plug in your coordinates). As the bullet or artillery shell is traveling through the air, it is not affect by the rotation of the Earth, but your target still is. In that distance, and when the bullet or shell exits the barrel to when it reaches its target; the target will have moved, be it ever so slightly (snipers) or over great distances (artillery).
I'll give you two accounts where the Coriolis effect played a crucial effect in history. First, the Battle of the Falkland Islands during WW1. When the British entered combat with the German navy, the British shells kept missing. Shell after shell into the water. ~1000 shells later, someone smart decided, oh it's because we didn't reverse our Coriolis coordinates! Nearly ALL of those 1000 shells missed the German boats by 10 miles+ to the left as they still had their old Coriolis coordinates in the Northern hemisphere where you aim left of your target, but in the Southern, you have to aim to the right.
Another part is the infamous Paris Gun. I'll give you an excerpt.
The Paris gun was used to shell Paris at a range of 120 km (75 miles). The distance was so far that the Coriolis effect — the rotation of the Earth — was substantial enough to affect trajectory calculations. The gun was fired at an azimuth of 232 degrees (west-southwest) from Crépy-en Laon, which was at a latitude of 49.5 degrees North. The gunners had to account for the fact that the projectiles landed to the right of where they would have hit if there were no Coriolis effect.
In summary of all this, to an observer on the ground, it would appear that the object, be it a cyclone or a bullet/artillery shell is curving left or right, when in actuality your trajectory is straight. To an observer ABOVE the plane of the Earth, that object is to be going in a straight line. THE ONLY THING THAT CAN CAUSE THE CORIOLIS EFFECT IS THE ROTATION OF A ROUND EARTH. So, regarding the FAQ, you believe in the effect (unless it's worded wrong). So therefor you HAVE to believe the Earth is rotating (and that it's round, it goes hand in hand).
*Also, from the FAQ again: you are saying the effect becomes less important as you are getting closer to the equator. So essentially it gets more important as you get farther away from the Equator. This is essentially saying the Earth is indeed round, as with the rotation of the round Earth, objects farther away from the Equator travel deflect left and right more than than an object on the Equator. FET essentially just proved itself wrong by saying they don't disprove of the Coriolis effect.*
Couple videos on it if you are having trouble. Highly regard watching these videos. All of them are no longer than 2 minutes.