Streaming video storage size (in the common file system measurements megabytes, gigabytes, terabytes, and so on) is calculated from streaming bandwidth and length of the media with the following formula (for a single user and file):

storage size (in megabytes) = length (in seconds) · bit rate (in kbit/s) / 8,388.608
(since 1 megabyte = 8 * 1,048,576 bits = 8,388.608 kilobits)

Real world example:

One hour of video encoded at 300 kbit/s (this is a typical broadband video for 2005 and it’s usually encoded in a 320×240 pixels window size) will be:

(3,600 s · 300 kbit/s) / 8,388.608 = 128.7 MiB of storage

If the file is stored on a server for on-demand streaming. If this stream is viewed by 1,000 people using a Unicast protocol, you would need

300 kbit/s · 1,000 = 300,000 kbit/s = 300 Mbit/s of bandwidth