Let us be positive and constructive, what should he have done to make it more believable and sincere?
For an apologie I would prefer to be standing and showing my hands (it is very difficult to look good on TV and showing your hands while sitting).
He should have used his own words and not a teleprompter (it was taped so if necessary he could retape it).
Should he have limited his response to his apology and not deflect to other issues, at least nog in this message? i'm not sure about that.