Lets be honest here, the DCR-DVD 91 is pretty old now at the time of writing (2012, I purchased it in 2005) most of what you can do you could probably do on a top end mobile phone or on a device with a hard disk to be able to upload it to your PC for fast access onto YouTube in this Do It Yourself media age!
That being said the features on this device are fantastic, and what you would expect from a SONY. You can record directly onto DVD for instant playback which is fab if you've had a day out with the family and want to watch it before instantly.
The quality of the disks is of normal DVD standard though it is not in high definition it does give a good picture using a 'carl zeiss vario-tessar' lens! Full screen (4:3) or widescreen (16:9) can be used.
There are night modes on the device so can be used in pitch black darkness (in a Blair witch style, which is so fun!)
All in all a VERY VERY good device, however don't kid yourself the device is equipped with features but these features would be available top end smart phone (in fact some smart phones can better the features of this device). However if you are not up for spending lots on a device getting these second hand or even new at a low price is a BARGIN!... I still use mine! As I don't like the thought of carrying an expensive smart phone in my pocket
Wonderful little device!!!