No, for the third time, it'll record from the beginning of the show or the beginning of the buffer, whichever is later. All DVRs work like that, because people don't keep pieces of shows. When they hit record in the middle its usually because they want to keep the whole thing.
I seriously don't understand why you have an issue with this.
So much wrong, so little time... Daretobe (lmfao) is asking the correct question, because all DVR's do not work like that, for instance the Dish VIP receivers do indeed record from the spot you push record if you desire. In fact it's the default at least on the 612, if you don't pick options it will record from where you pushed record. And I use that the most because people do want to record only a section very often.
I seriously don't understand why you have an issue with this.