I would say for the past week, when streaming videos (most commonly on YouTube) they will always buffer constantly when in 1080p/1080p60fps. (Sometimes it will do this in 720p/720p60fps from here and there)
Speedtests to Shaw and others come back at fine speeds (Internet 30). I get an average of 33Mbps down and 5Mbps up on Speedtest.net.
I've tried on Chrome and Firefox and still the same thing happens.
I'm on a wired connection, and this occurs on all devices (2 Windows based PC's and 3 Modern Android Smartphones).