Buffering or Stuttering with Low Latency Streams?

Seeing this happening on a couple different machines, in FF, and does it in Chrome as well.

The stream starts at the 640 x 360 resolution. But when I switch to a higher resolution, after a while, I see the stuttering that you see in this video. The stuttering/buffering starts at about 2 mins and 50 seconds into this video and continues.

A speed test shows 85 Mbps down.