It looks like there are at least three factors that affect the practicality
of video that is distributed over the Internet.
1) The speed of the network connection.
2) The data transfer expense for the video server.
3) The quality of the codec.
A year or two ago, I might have included the capacity and cost of mass
storage as a fourth factor, but with 250 GByte and larger hard drives on the
market today at prices of less than $1 per Gbyte, it seems that storage is no
longer a limiting factor.
The remaining three limiting factors are inter-related. A fast enough
network connection can compensate for video that is not highly compressed.
A very efficient method of transferring files, such as BitTorrent, can
compensate for video that is not highly compressed. Video that is highly
compressed while maintaining an acceptable quality of display can compensate
for both slower network connections and less efficient file transfers.
Most people with broadband Internet access today have a realistic connection
of about 1 million bits per second (Mbps).
A more efficient, distributed file transfer technology such as BitTorrent can
reduce the load on the video server by a factor of at least two or three, and
possibly much more for very popular files that are being downloaded by many
people at the same time.
The best video compression technology today can provide a VCR quality viewing
experience at a data rate of about 500 kbps. An hour of video at this level
of compression requires about 225 MBytes of storage, which again, is not very
demanding of today's storage devices.
