Another thing to note. The stutter (every 5 seconds a freeze frame) is consistently reproduce-able on Gnome on Ubuntu 18.04 but when you switch to Unity there is no stutter the video at all. So suspect that Gnome could also be playing a part in this issue.
Another thing to note. The stutter (every 5 seconds a freeze frame) is consistently reproduce-able on Gnome on Ubuntu 18.04 but when you switch to Unity there is no stutter the video at all. So suspect that Gnome could also be playing a part in this issue.