The XIR by greengiant has nothing to do with that video. That video is a demonstration of the new PC-NitroXX with optional IR control add-on. You can select different BIOS banks, turn Xbox on/off and eject the tray with the remote. It looks very kewl but this require the PC-NitroXX and cannot be used with other modchips.
The XIR Easy by greengiant is simply used to turn on/off the Xbox. I bought one and it works great. I highly recommend it if you do not have the parts and ability to make one yourself (or are just lazy like I am).
I did not wire up the optional D0 control, but I am told that if you wire pin17 on the XIR to D0, then you can enable or disable the LPC modchip depending on whether you use Display or Select button on the remote to turn on the Xbox. I presume you have to remove D0 connection from original LPC mod, because of this I imagine that Matrix users may need some further modification. I don't consider this a real important feature though and the ability to turn on/off Xbox via the IR remote is just so kewl.
I am sure you could modify it to eject the tray on power-on instead of D0, but I am not sure what real usefulness this would be in real-world situation. If you eject the tray remotely, are you going to try throwing a disc in it from across the room?
Usually when you put the disc in, you are in close proximity of pressing Eject.