The control was in the hand placement which stayed constant throughout the entire experiment, which showed intact voice quality. The variable was the extra finger moving down the side until it came into contact with the insulator portion. The observation was that once the finger progressed to the insulator portion, the reception/transmission was cut.
That's an experiment.
Was the finger wet? Did he lick it first? Was it hot in the room, causing him to sweat? What was underneath the phone? Did he have a paper clip taped to his finger? You get the idea. YouTube is not an authoritative source for news and what folks are doing is hardly scientific. I'm not saying they aren't experiencing issues (they obviously are), but the cause has not been determined yet and everyone is just guessing (or assuming) it's the antennas when earlier models exhibiting the same symptoms would seem to indicate something else.
"One iPhone 4 demonstrated the issue everytime it was held in our left hand (as a right-handed person is apt to do) so that our palm was essentially bridging the two antennas. You can see that in the video after the break. Bridging the two with a finger tip, however, didn't cause any issues with the reported reception. If we had to guess, we'd say that our conductive skin was acting to detune the antenna -- in fact, we've already managed to slowly kill two calls that way so it's not just an issue with the software erroneously reporting an incorrect signal strength. That said, we had no issues when Apple's $29 rubber bumper accessory (given to us free for standing in line) was attached, creating a buffer between our palm and the antennas. Our second UK-purchased iPhone 4 was fine, showing none of these handling symptoms. See the video evidence after the break including Insanely Great Mac's version which got us to worrying in the first place."
There is obviously more going on here than just the external physical location of the antennas. The phones don't look physically different, yet some iPhone 4's exhibit symptoms and some do not (including 3G and 3GS), which don't have external antennas..