I thought I had answered your questions. If the main thing you really want to know is
The itach wifi2ir doesnt have to be pluged to pc or to tv?
then the answer is no, the itach wifi2ir doesn't have to be plugged to pc or to tv. Wifi is
wireless. That is how laptops and iPhones are able to communicate without wires. IR is also wireless which is why you are able to point your remote control at your TV and control it without running a wire from your remote to your TV.
My wifi2IR came with a "blaster" emitter which I show in the video. It connects to the unit and sends out the IR signal. Whatever you buy make sure it comes with an emitter or buy one separately if it does not.
You either need a blaster emitter for controlling from a distance, or a stick-on emitter like the last link you posted if your device is in a cabinet so that you cannot see it.
You need line of sight or you can use small emitters that stick on to the front of your AV equipment if it is hidden away in a cabinet for example.