video/audio file anti-leeching

I have joomla and vbulletin powered site running video and audio streaming. Because my main server's bandwidth is limited, I will expand to host the files in external server B or C and so on besides my server A. 1. The real link to the file on both server A and external B has to be completely hidden (even from IE temp folder). don't care about the methods, it could be done by using token-based or URL scramble system that only valid for like 20 mins, or any other ways is completely ok. 2. The file on external server that link to the main website should NOT takes the bandwidth of the main site. My current PHP script hide all the link completely, but when I link to external server, the bandwidth is cost on BOTH server. One programer explained to me: "If you have the file sitting on another server (say server B)and you hide it, then all the traffic has to pass twice through your server (server A) - once to read the data and once to send it to the user" 3. I'd prefer the external server to be a hosting space only, but I can have PHP installed on the external server if it's the only way to meet my needs. I hope I've made my requirement clear, please let me know if you have any questions. Thank you.