It is reasonable to presume that he did not tell his Barrister about the CCTV. He , himself , may not have known, depending on how it was taken , and retrieved. His counsel appeared to be a bit shellshocked at the quantity , and probably, the quality of the matters disclosed by the prosecution. It is reasonable to assume he is not talking to police. It is unusual if he is not on speakies with his own barrister, that presents monumental problems all round.
It would be redundant and a total waste of the courts time and resources if there were to be a trial if he did, indeed, make a full and frank confession. That would preclude and negate the reason for a trial, the judge would go straight to sentencing. He would get some pro rata discount on his eventual parole date, at this point probably a months worth, instead of years, because the entire point of pleading guilty is to not waste the courts time and money. He is, anyone is , rewarded somewhat for that. But it is not essential, depending on the public perception of the crime, some crimes just do not get that discount, guilty or not guilty plea.
It is really not a matter of anything can happen, logically, some things can be ruled out. He may suddenly desire to blab about everything. I doubt this, because it appears to sustain him, and there are not many rewards, or favours he can expect at this point. VICPOL will never give up on the search for Mrs Murphy's body, he knows this, his barrister would tell him this, it's only a matter of time.
His crime is , in the public perception, so hideous that the judge would be reluctant to decree any discount no matter what he pleads. guilty or not. No one is going to bargain the charges down in the hopes of getting access to Mrs Murphy's body, , this is not going to happen, VICPOL will not bargain with a murderer. He is not going to have any say as to where he serves his sentence. He is not going to have any input into what treatment for any health problems he may claim to have. He is not going to be able to choose which level of custodial observation he will be placed under, and so on. lots of stuff like this.
It is not unreasonable to presume he will not make any statements about this murder. This is not the usual, but it is also not unknown. My own perception is, he may have bragged to someone in Remand, and this will be exposed come trial time. Remand is a lonely occupation, one is neither one thing, nor the other, but one is locked up , with people one would not usually break bread with, one is away from home and family, from one's regular routine, it's all very stressful , and he is very young, in that respect. He may, just may, crack on about it to someone sympatico.