It's a complicated issue and it depends entirely on the crime. But, yes I think there are circumstances that certainly call for a youth offender to be brought up to adult court.
Not all cases of youth murder are brought up to adult court, it's usually the ones where the crime was deemed so violent that it can't be written off as a case of the kids making a mistake or just having immature and improper judgement (there is also an evaluation into the mental maturity of the offender/s, but the weight of that varies). Just the fact that the crime has been brought up usually means the nature for the 'promotion' accounts for why the sentencing is usually harsher in the cases of juveniles being tried as adults.
There's a difference between being young and making mistakes and being young and being a cold blooded killer. Drinking and driving offences, some cases of manslaughter, possibly some murders of circumstances, and the like can be argued that it's a young person who doesn't know the reprecautions of their actions and the effect that they would have on their victims. But (taking a case out of the papers here), when two teenagers get baseball bats and bludgeon a random old man in a public washroom (who later died), go home get heavier bats the next day, return to the same bathroom and kill another elderly man that's just a case of two people who have shown such violent tendancies that they should not be tried differently than any other killer. Would maybe four years or so of wisdom have changed their actions? It doesn't fucking matter. The purpose of the criminal justice system isnt based soley on rehabilitation.
I take it this is the episode you saw:
http://www.pbs.org/wgbh/pages/frontline/shows/juvenile/Having written a pretty extensive paper on the Young Offenders Act, the reasoning behind it, statistical evidence, and criticism of it I can confidently say that you're not going to get a real view of how the system works from an arguably sensationalist 1 hour television show. The flaws associated with the juvinile/adult interplay are just symptoms of the general flaws associated with the justice system in general, and will remain so unless every crime is looked at as a statistic rather than a story.
