Typically videos will go low resolution when bandwidth requirements are not met.
I would run a internet speed check on your PC https://www.speedtest.net/. Be sure you do this either hardwired via Ethernet or as close to your wireless router as possible. If you are in fact on wifi then the quality drops could be a poor signal either caused by distance or by too many devices on your wireless network or on other wireless networks like in an apartment.
I prefer www.speedof.me but anyway
Playing games has nothing to do with the quality of your internet connection.
If your quality is low/bad you will get the best image possible for that speed.