As we know, one of the most common problems of Windows Operating System is that it can not upload files fast or in its real time. The problem is not with its hardware but its "core" or central processing unit. Windows OS crashes due to CPU issues more often than you think. One of the most common reasons for Windows OS crashes is Windows "incompatibility". The trouble with this is that its registry contains so many important files, which can be corrupted if some recent hardware changes and cleaning are not done.
Now let us move on to the question how does Windows Fast Upload work. If you are having a good internet connection (ISP) and you are trying to use Windows OS to stream video then you should make sure that your internet connection is of high quality otherwise your Windows Fast Upload will not work properly. Internet connection quality largely depends on your internet service provider (ISP). If you have a dial up connection then you should try to upgrade it to a broadband connection or switch to a cable modem (DSL or Cable modem) to increase its quality.
If you are having a dial up internet service, then also try to upgrade to a higher broadband speed. You can do it by contacting your internet service provider and ask to upgrade your dial up internet service. If you don't want to upgrade then try to find other ways by which you can improve your internet service quality. Or you can also try for another type of connection such as a satellite internet or cable modem if you have one. So, you can see, having a slow computer or a slow internet service does not mean that you should be deprived from enjoying watching streaming videos on Windows OS.