It works quite well, actually.
As Jimbos said, you will record just in 480i, but it is a great way to archive programs.
Let's assume you have one set of outputs going from the HR20 to the TV.
You really can not hook the satellite cables directly into the DVDR, they have to go to the receiver first. Then you take the receiver (HR20) output to the DVDR.
You would just hook up a second output from the HR20 and input it to the DVD recorder. Then take a DVD out to another input on the TV. This way you can monitor what you are recording. Keep in mind, as you are recording, make sure you don't change channels on the HR20, as this will change what the DVD records as well.
Some TVs will allow you to capture their output, but the above method is probably the most easy to implement.
One of the nice features of the HR20 is that the analog signals are automatically 480i, even if you are watching on a HD set at 1080i or 720p. I have a HR10-250 and had to set the output to 480 to record to DVD, then I would forget to re-set to the HD format to watch regular content.
I upgraded my Phillips DVD recorder to a Toshiba RD-XS32 which has a hard drive. I can edit out commercials then record to disk. If it is a long program, I will start the transfer when I go to sleep, and the Toshiba allows me to specify a time to stop recording and power the DVD recorder off.
With the Phillips, you can pause during commercials if you wish. I was pretty impressed with it, but found the HDD to be a huge help by being able to edit on the HDD, then dump to DVD.
Feel free to send me a PM if you need more help, I would be glad to help.