Defense is the weakest part of my game. I have no problem admitting that. In all seriousness, it is true and so I'm throwing this discussion regarding defensive alignment out there for clarification or correction by you all. Think hivemind. Help all of us by correcting anything that I've written.
I also picked this play because it was clear where the players were lined up and we actually got a look from the perspective behind the quarterback. I thought that if I could try to point out what I know, that it would make it easier for me to discuss.
Let's first take a look at the defensive line. I think the nose tackle here, the line over the right guard, is lined up at the inside 2 technique defensive alignment, which is the gap between the guard and the center, but shading towards the center. Then the defensive tackle is at the 3 technique defensive tackle spot.
In a way, the defensive tackle is playing the somewhat famous 3 technique that made Warren Sapp so great, but normally in that type of scheme, the nose tackle is shaded over the center not the guard like it is here. Where the nose tackle is aligned is usually a good indication of the strength of the formation as the nose tackle will shade towards the stength of the formation (i.e. the side where the tight end is). In an over 3-4, the nose tackle shades away from the strength of the formation.
The interesting thing here is that in a true 4-3 under front, the defensive ends will line up at the 5 technique, which is what Texas Tech has done here, but the distinction is that the nose tackle is supposed to line up at a 1 technique, not at a inside 2 technique.
I'm thinking that the purpose is the same as the 4-3 under in that they want to essentially get the 3 technique defensive tackle one-on-one, which is normally Kerry Hyder and intended to make sure that he's able to do some damage.
The other interesting note is that the middle linebacker should be shaded over the inside leg of the nose tackle and I think that's Blake Dees and I think he's lined up correctly. The strongside linebacker is supposed to be lined up directly in front of the tight end, or on the outside leg of the defensive end. In this case, the strong side linebacker is lined up right behind the defensive end.
The weakside linebacker is not in the picture, but I'd imagine that this is some sort of safety or linebacker that is lined up over a slot receiver.