Hi i would plan to make something like YouTube (video sharing site) but restricted only for my members. Basically if let's say there are 1000 users every day streaming videos on my site, how much bandwidth do I need and how big the server has to be considering this isnt just regular site but video sharing site for members?
You'd need a crap load of bandwidth... If it's in your budget, i'd go for a Quad Core Xeon if you can.
You won't need a heavy-duty CPU to process videos if they are being streamed although power is always a good thing, but you will need lots of bandwidth in the truest sense of the word i.e. not data transfer (you will need that too) but actual bandwidth in terms of pipe size, and if you can, fast disks. We had a customer recently who uploaded a very popular single video to their VPS that was getting around 6000 downloads a day between 08:00 and 22:00. The VPS had dual virtual CPU's and 4GB of ram and the CPU usage never climbed above 5% and RAM remained at about 900Mb (it was a Windows VPS), but their bandwidth climbed to over 35mbps at peak times (equivalent to around 11,200GB a month). The VPS was using 15K SAS disks with a 128MB Cache RAID controller so this took care of dealing with the traffic in its stride.
If your streaming that large amount of content I would suggest you getting a dedicated server at 10tb, their site can be found at www.10tb.com
You may not use a lot of space and bandwidth, but your web site will use a lot of server sources and that could be the main reason why you need something bigger than shared web hosting account.