Thanks again Allan. I contacted Online Chat Support.
According to them, it seems this is expected from the NUC.
My chat transcript is below.
info: You are now chatting with 'Alberto'
Alberto: Hello. Thank you for using the Intel Customer Chat Support service. We are glad to be of service. How may I help you?
Karan: Hi I am trying to figure out if there is something wrong with my NUC
Karan: I have a D54250WYKH, I have a abnormally high CPU usage when using a web media players. Around 42 to 56% of CPU usage when playing a video from Netflix or Amazon Instant Video. When when multitasking, the video would lag.
Karan: any issue is addressed in this forum thread: https://communities.intel.com/thread/56635
Karan: I already have the latest BIOS and Graphics drivers.
Alberto: I'll be more than glad to assist you with that
Alberto: Have you tried a BIOS update?
Alberto: what is the BIOS version on the NUC curently?
Alberto: where are you seeing those values?
Alberto: reference number: 6994968
Karan: The values are shown when trying to install the latest BIOS
Alberto: yes, thanks
Alberto: but the values in regards to the CPU usage?
Karan: Task Manager. in Processes and Performance Tab
Karan: I can take a screen shot if needed.
Alberto: which windows do you have?
Karan: Windows 8.1 64bit
Karan: idle CPU usage can be below 9%. But while playing a 1080p video on for example YouTube the CPU usage is upto 50 - 60% constant.
Alberto: I see
Alberto: yes, actually that is expected
Alberto: the CPU usage can fluctuates
Alberto: and it is up to the NUC itself
Alberto: to increase it or crease it
Alberto: decrease it
Alberto: according to the demand
Karan: I understand that, I issue if of video lag while multitasking. Is that normal for the NUC?
Karan: I understand that, the issue is of video lag while multitasking. Is that normal for the NUC?
Alberto: I see
Alberto: so the NUC gets freeze?
Karan: Not the whole system, Just the video lags
Alberto: yes, that is exepected
Karan: I use less powerful CPUs like 4th Gen Core i3 or i5 with HD 4400, that work fine. Its only the NUC which does this.
Alberto: specially if you are using applications with high demand on video
Karan: Ok if that is expected from the NUC thats fine.
Karan: Thanks for your help.
Alberto: You are welcome
Alberto: have a nice day
It seems I am not the only one with the Issue:
There's no point getting a replacement, as it would have the same problem, I will just see if i can return it.