Your form looks pretty good. The way your body is built you have the potential to be a very good deadlifter. Please also keep in mind that the below points are coming from someone whose goals (maximal strength) may be different than yours (please fill me in).
-You are forecefully trying to keep your back flat. This is fine, but may not be optimal for lifting maximal weights.
-You drop your hips too far at the beginning. The way you are built you will have better leverage with starting the pull with your hips slighly higher. I realize this may be contrary to what you read about technique, but the deadlift is all about leverage. What works for one person may not work for the next.
- You lower your hips, relax your arms, and bend at the elbow. Flex those triceps! DO not try and start the movement with your bicep contracted at all. This is a bad habit that should be stopped now. Notice where your hips are when the bar breaks the floor. Kind of hard to do in this video, but that is where you want to start the movement.
- With your long arms, in addition to the higher hip position you may benefit from starting with your shins a couple inches further back from the bar.
- Your wife has a very natural fluid technique. In other words, she doesnt look like she is thinking about what she is doing. But she appears to be unlocking her knees at the top.