In the time it takes for someone to say "Xbox, record", someone else can easily press the PS4 share button before they're finished saying it.
Anyway, I thought the majority of people disliked the Windows 8 Metro UI, which this is based off of.
"Record that" or whatever it is saves the previous 30 seconds I think to a separate file. It's always recording. You can get more than that by calling up the game DVR.