It`s not on the computer specs, but on the internet speed.
Depending on the interface of the game, it might use most of the internet bandwidth that it can, even all of it until it finished downloading.
This means that there`s no bandwidth remaining for the video you`re watching (downloading).
The thing is that the video that you`re watching is not located on your PC, but on the internet, so the "image" needs to be also downloaded by the PC for you to see it.
Don`t worry, there`s nothing wrong with your computer. It`s just the way internet bandwidth and internet speed work.