I've watched various videos, and it's the latest version of Flash and all appropriate settings.
I turn the videos up to 4K (2160P) and they chop a little bit ... like every frame isn't smoothly seen.
Also, I am using a 50 MB internet connection, but the video buffers non-stop and barely plays.
GPU: HD 4400.
OS: Windows 7.
CPU has a Passmark of almost 2,100, 4 cores (with hyperthreading), and 3 MB cache. I believe the CPU can't really be bottlenecked by 4K video streaming. Could the GPU be struggling in this case?
I don't know how much of the CPU vs. GPU Flash Player uses, but 1440P plays 100% perfectly.