Being a tall myself, 6'7", I understand the difficulty in both these lifts.
Due to our height we can take a much wider stance in squats. When it comes to your feet I've found its beneficial to "duck foot" a little, so just cock your feet out a little bit. A good way to remember proper squat form is this saying: "disengage the hips, tighten the core, split the floor." So the first move is unlocking your hips (like Cork said). Use an empty bar to practice at first and get the feel of it. Stand there and then just cock your hips back like your trying to stick your ass in the air. Then tighten your abs and keep them tight!! When you start coming back up from the down position act like your trying to tear the floor with your feet, this will keep your knees from turning in.
As for deadlifts... There may be a lot of people that disagree with what I'm about to say but there have been studies that prove it and that's good enough for me. The first 6" of the deadlift are POINTLESS! Studies have shown there is nothing to gain from those first 6" other than back problems, this goes for tall AND short people. So do rack deadlift or throw a couple 45lb plates down on the ground and set the loaded bar on them. Anything to negat those initial 6. This is ESPECIALLY important for us tall people as the deadlift puts our lower backs in a more compromised position than those shorter than us. Also, like Cork said you hyper extended your back on the last set. I can understand his point of max effort but there really is no point in doing that unless your competing. The whole reason the hyper extension was thrown into deadlifting was to show the judges that you've fully locked out. With DL's just as with squats you can take a wider stance, with those first 6" inches taken out of it though I've found I don't need to do that anymore. Oh, I didn't look at this when watching the video, but your hand position with DL's... when first learning proper form with this exercise go with a double overhand instead of the common over/under positioning. When your not familiar with DL's or still in the learning faze you can tear a bicep in the over/under and you really don't want that! Plus the double over makes you concentrate more on your grip which is very important.