I downloaded the video and watched it and what he is seeing is consistent with what I have seen as well although I have not seen it on a mac pro, only on mac minis. There will be no frame dropping, the meters will barely be pegging anything and I will see what he calls "tearing." It is typically only with videos that have a high data rate/ fast motion in installations that I have done.
I assumed this was because of the fact the minis have integrated graphics card which is not very good. We stock them all with 16 GB ram so they effectively have 786 MB of video memory, coupled with SSD drives, which I would think would be OK for 1 layer of 1080, 30 fps without issue.
I can verify that remote desktop and network traffic seems to intensify the problem. Pro-res proxy codec seems to make it work better but I had this same issue with some old stock SD content in photo jpg, 1 layer….
I assume it has something to do with the graphics card not being able to keep up in some way. I am not that well versed in how graphics cards work or how they play into the equation but it would seem if there are no dropped frames, it isn't an issue with reading the files off the SSD. Tried a triple head on a mini at 720x3 just for fun and noticed this same type of issue, so again I presumed it is just that the graphics card can't handle it. Not sure why it would happen on a mac pro with a quadro?
