I was quite surprised how jolly it all was and very out of keeping with most people's perception of the US jail system. I suspect there was a lot of careful selection of the prisoners to select only the ones that were happy, jolly, resigned and getting on with it.
For me the most surprising wasn't the guy with 521 +11 life sentecnes (who after all knew he did it and he deserved it) but the young black guy who swore blind he was innocent and STILL seemed fairly content to get on with doing his time.
They only touched v. lightly on the sex-offenders (the guy who's crime was 'to let a DEMON take over my life') and I thought that was something that was a bit too rich for the BBC's stomach.