Here's something for ya...
It seems this bad Quality problem is actually coming from the GXV3140 phone.
I have a Yealink Video Phone here which does not seem to have the same Video Quality issues as the Image Quality is pretty nice and sharp unlike the Grandstream that makes the image blurry every time you move an inch.
Grandstream GXV3140
Honestly, the Yealink beats the GXV3140 in every aspect in my opinion.
The Grandstream is slow as hell, it took me 1 and half hour to upgrade the firmware, the phone it's self often gets stuck because of the slowness of the interface.
It can play Videos / FLV / Flash / MP3 / Connect to sites like youtube, Facebook, radio, web browsing twitter and many others and do a bunch of stuff that an office phones doesn't need to.
It's simply too slow to use as a phone. When you dial a number, the dialer delay is so much that it shows up after 2-3 seconds sometimes, and you can even make the phone freeze by attempting to Dial a number.
I'll give it points for having nice looks.
Yealink Video Phone
While the Yealink on the other hand is like having a Modern Android Phone, it gives the feel of an i-Phone, and the interface does not lag at all. Everything is as it should be.
It supports fast switching between 20 different accounts with 2 taps on the screen.
This is more of an office phone with all "Needed" features rather than the "Media Center" phone grandstream provides.