First set of 245 - I went with a wider foot stance than I normally do. I also tried keeping my back straight all the way down on my approach rather than trying to set up while I'm down at the bar. It both felt and looked very awkward.
In my experience, this doesn't work well at all. The order that works best for a proper deadlift setup is:
1. Feet: use the stance width you use for a two foot jump. Setup with the bar over the middle of the foot, some ~2" from the shins for most people.
2. Grip: bend at the hips (not the knees) and take hold of the bar
3. Shins: now bend the knees forward until the shins touch the bar
4. Chest: suck in a bunch of air and tighten up the entire back into an arch by "lifting your chest" (think of doing supermans on the floor)
5. Pull
Here is a good video of
Rippetoe teaching the deadlift setup.
Watching the video, I noticed that I was starting with my hips pretty high, so on the second set I tried lowering them. The result was my hips moved out of sync with the rest of me and it felt heavier, so maybe the high hip approach is better.
It's a deadlift, not a squat. The hips should be fairly high. If you start too low, they'll just shoot up anyway, which is exactly what happened on your second set.
The first rep of the first set was actually decent, although using the setup above may make it even better. However, the problems start after the first rep: you don't lower the bar down correctly (you bend your knees too early), so it ends up too far forward. As a result, your knees come forward more, and as you do the second rep, you are fighting to get the bar around them. The bar is further from your body, your hips shoot up, your back rounds a bit and you are forced to do the whole pull with your hamstrings. I think three things will help:
1. Lowering the bar is done in the exact opposite order of pulling the bar: you push your hips back first and only as the bar is clearing the knees do you start bending them. It should slide down your thighs and shins on the way down just like it does on the way up.
2. Even though the deadlift is called a "pull", it's better to think of it as two pushes. The first push is you driving your heels hard into the ground and the second push, done once the bar is clearing the knees, is to push your hips/ass forward. Most people screw up the first part: they start pulling immediately with the hamstrings, which causes their hips to shoot up, and the knees to unbend, taking the quads out of the picture without the bar having moved an inch.
3. You are craning your neck a lot to look forward. The neck should always be in neutral alignment with the rest of the spine; since the deadlift starts with the torso fairly horizontal, looking straight ahead is not a safe or natural position for the neck. Instead, look a bit more down at a spot on the floor several feet in front of you.