ORIGINAL: quiksilver
It looks like to me that he doesn't have the STS anywhere near his string, thus, it is doing nothing for his bow. It should be against or just slightly off of your string at the resting position of the bow.Maybe not totally, but almosteliminating the string travel past the resting point. This will give you a smooth quick detachment from the nock, and in most cases, adds speed to your setup. I shoot a Switchback XT with an STS, and it shoots quiet, smooth and fast. I personally have seen no ill effects from the STS.
This person's STS is so far forward, that the string is in full forward position, and still isn't in contact with the STS, which should be positioned even with his string suppressors, but it looks like it's a good 2-3" in front of them!
Look at this picture, and it might change your opinion.