Unfortunately the earliest interview was recorded on audio only, and the recording is extremely noisy. I tried to clean it up using noise reduction techniques, but nothing helped. It really seems unusable, because hardly anything said is clearly audible. The sound on the videos, however, is adequate, and despite the very annoying dropouts in the second one, there is more than enough important information that comes through loud and clear.
It's been alleged that Brendan was manipulated into implicating Steven and manipulated into confessing to his own role in the assault and murder, but I see no evidence of that. While his interrogators strike me as rather inept and their continual reassurances that they are on his side are certainly dishonest and misleading, as is their insistence that they already know what happened, which is probably untrue, it's impossible to imagine that he would have made up so many incriminating details simply because of their inept and annoying persistence. I see no evidence that they told him what to say, though they do ask leading questions. There are plenty of places where he volunteers information he obviously hasn't been fed. And much of what he says in those places is devastating to Steven Avery's defense. The notion that he'd been fed a made up story in advance strikes me as yet another example of Avery's lawyer's ludicrous attempts to base their defense on some sort of grand, wide-ranging conspiracy theory. I see no reason for the investigators to concoct such a story and certainly no reason for Brendan to go along with it if it's untrue. As for the absence of a lawyer during the interviews, he was read his Miranda rights and agreed to testify without one.
I've seen many police interviews where the interrogators loudly accuse suspects of having committed a crime and act in an extremely intimidating manner in order to break down the suspect's resistance. This does not happen here. While the interviewers are persistent, they are also respectful and patient, and speak in consistently soft tones. While their insistence that they are "on his side" is misleading, it is also true that, had he agreed to testify against his uncle, they would probably have helped him get a reduced sentence as part of a plea deal.
Brendan testifies that he was with Steven when the attack took place, that Steven invited him to join in on the rape, and that he did so, that he saw the victim's vehicle in Steven's garage, saw her dead body in the back and helped his uncle burn it. Brendan is clearly upset and frightened, which explains why it takes him so long to get things out and why he is so uncomfortable. While there may be some inconsistencies in his statements, that is understandable in the testimony of someone who sees the sword coming down over his head and can hardly be expected to be completely cooperative. We also have to realize that his whole family has come out strongly in support of Steven, so what he is now saying will certainly get him in a lot of trouble with everyone he's ever been close to.
We see similar evidence of intimidation at a later point in the film, where Brendan's cousin, a fifteen year old girl, testifies. According to a statement she provided on an earlier occasion, she saw Brendan crying and when she asked him why, he told her the whole story of helping Steven assault and murder Teresa. On the stand, she is extremely uncomfortable and begins to cry. When shown her earlier statement, she denies it, and when pressed to tell the truth, she claims she was lying -- giving no reason for why she'd lie about something like that. While technically a lawyer could probably get her earlier statement removed from the record, to anyone with any understanding of human psychology it's clear that she's under tremendous stress from a family that would see her as a traitor if she testified against Steven.
7. Possibly the most despicable episode in the film is the segment where Brendan's first lawyer is vilified because of his refusal to insist on his client's innocence. The implication being that no decent lawyer would turn on his client like that. That is simply not true. As I see it, the lawyer must have realized that Brendan had fatally implicated himself already and any attempt to defend him as some sort of innocent victim of "the system" was bound to fail -- as it certainly did down the line, for both Steven and Brendan. The lawyer obviously decided that a plea bargain was Brendan's best bet. If he had agreed to testify in Steven's trial, then he could probably have gotten off with a relatively light sentence, especially because he was both young and mildly retarded, and thus could easily have been manipulated by his uncle.
Steven's family and his legal team must have realized the implications of such a plea deal and would have done anything in their power to prevent it. So they made a huge fuss over the "incompetence" of the first lawyer, and got him replaced by a lawyer willing, essentially, to toss him to the wolves (literally) by refusing any deal and forcing a separate trial. The devastating result was entirely predictable.