When doing video chat on Messenger with my Galaxy Tab S2, my video image appears blurred on the recipients screen, see
attached photo (which was sent to me from a recipient). The recipients video image appears clear and fine on my screen. What's it about? 
Could be for different reason, bandwidth use with adaptability to it, automatized codec, settings in the app, device.
You can try to define video as maximum quality level, also a good quality from the Internet connection will help to maintain max qualities.
Other important thing, you are using front camera our friend, then your maximum resolution will be of 2.1 Mpx in front of your rear cam with 8Mpx and video 1440/30fps.
With 2.1 Mpx is a low quality range in front of actual new devices with more resolution and definition with new technologies to agile internal process as a 5Ghz Internet wifi connection too.
Be sure your lens are clear for improve quality too.
I think is not a problem, it is correct for that good tab that you are using during long time and I wait you continue with it 
