I didn't get any video of his first couple attempts but after we got home, Little Brother gave it another go. By golly, we've got a house full of pedalers now! There is no fear in this kid at all and he's riding a full year earlier than Big Brother's first tries. There's still much work to be done--power pedal starts, braking, proper lane positioning, etc. but I am so excited!
Here is a short compilation of his afternoon progression. Forgive the crappy editing (by which I mean total lack of editing) and out-of-focus video. My kid can ride a bike!