system
Given the following post, respond as if you're commenting on Reddit:
human
Why is it that you can stream >1080p HD quality video with surround sound, but video calls like Hangouts looks like you are communicating via potatoes?

I get that it is using UDP and that packets are not guaranteed.  I also get that you are uploading as well as downloading and are at the mercy of the upload speed of both sides.  But those reasons do not sit well with me given that when I try to call my dad who a) is in the same city and ISP and b) we both have sufficient upload speed (enough to stream HD videos from home, ie via plex).
gpt
You also have to consider that streaming video is either a full file being served in parts (streaming a movie), or on a sizable delay (a "live" broadcast). This allows a buffer where the content can be downloaded ahead of being displayed. It also allows a program like Netflix to seamlessly switch between HD and SD if your internet connection speed changes, because it has enough warning ahead of time to make the changes.
  
With a video call, latency is everything and even a 1-2 second delay is frustrating when trying to have a conversation. To ensure super low latency, video quality suffers in this tradeoff.
  
Also take into consideration that most front-facing cellphone cameras and laptop cameras are made to be small and cheap, with low resolution captures. You're comparing a movie (shot with nice high end cameras with good lighting) to a shot of yourself in a dark living room with a camera smaller than a dime.