As long as the device you are recording with has a TV tuner built in you won't need an IR blaster. An IR blaster will turn on your cable box, sat reciever etc and change it to the right channel for recording.
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To expand on Rwwear, the blaster is an IR output from the dvd that will send commands to other pieces of equipment to control them. ie the dvd player can turn on your cable box and switch it to the correct channel when it is time to record. Some blasters just use IR repeaters while nicer ones actually can plug into the IR in in the back of another unit (this avoids any interference).