Akamai Edgescape

Bear in mind that the files may be cached elsewhere as well, including at any proxy servers that the client is behind or in the browser's cache itself. An easy way to get around this is to add a query string to the URL, and change the value each time you update the files, or set it to a random value to bypass the cache each time. The server will ignore the query string, but the browser and proxies will think it is a completely different URL and re-request it.

For instance, instead of requesting:

styles.css

request:

styles.css?version=1

Akamai provide an API to allow your customers to download files.

From their web site it is called "Client-side Downloads"

Client-side Downloads offers the ability to offload a significant portion of edge delivery onto a managed and secure network of clients - using client-to-client delivery - to provide a lower cost download solution that respects the clients. Good uses may include software downloads, patches, and updates, background software and drivers, and downloadable video and games used by about a thousand or more people.

http://client.akamai.com/misc/demos

Here is further detail on how to interact with their API

http://client.akamai.com/misc/demos/csd-index.html

I was at their presentation the other day and they spoke about a Video Stream product coming out mid to late 2012.

I ran into another company that did video hosting and streaming called Movideo