This depends on the PVR and on the PC, if both have a USB socket it is fairly simple and quick. The use of firewire is even faster but there are very few PVRs with this feature.
If not you have to connect a video output from the PVR to a video input on a capture card.
If you also wish to transfer the sound track, you must also connect the audio in and outputs, then you have to play the video on the PVR whilst recoding on the PC.
This is a very slow process that takes the same amount of time as the film lasts.
On a PVR from DSTV the usb port is not activated and the outputs are encrypted so you can't copy to a hard drive from it.