[Ed Miller]

Its almost highly unlikey he's folding here and not seeing the river.

I'm sorry Mikey, but that's just not true. I can't prove it to you other than to say, "Go try it out," but often the flop bettor will have a small pair or ace-high (especially online) and will fold it on the turn.

Frankly, I don't understand when people say stuff like this, because it flies totally in the face of all of my experience. People fold all the time on the turn after betting the flop. I'd suggest you watch online games for a while, note who bets the flop, and watch to see how often that player folds on the turn and river. You'll find that it happens frequently. Not all the time or even the majority of the time, but it's quite common.

Would I be wrong to take a free river card and not bet the turn? How much of an error is this?

If more than one player had called you on the flop, taking the free card would probably be better in general. So against one player taking a free card can be no disaster. But you will often win this hand without a showdown, so it is clearly right to bet again.