Optimize nginx stream

we’re running high traffic streaming website similar to youtube, due to
large number of streams on daily basis, our server is consuming 10~12TB
bandwidh per day. We’re using nginx-1.2.1 and want to restrict users to
download videos but don’t want to restrict streams from our website. We
also tried "limiting download connections per ip (limit_conn addr 1),
the problem is if 2~3 users are streaming videos from our site on same
with single ip, the stream will stop working for 2 others and will
(stream not found) error .I am newbie to nginx, can anyone help me on
optimizing bandwidth security for nginx? My particular host config
are given below :-

limit_conn_zone $binary_remote_addr zone=addr:5m;
server {
listen 80;
server_name content.com;

    client_max_body_size 800m;

    limit_rate 100k;
#    access_log  /websites/theos.in/logs/access.log  main;

    location / {
        root   /var/www/html/site;
        index index.html index.htm index.php;

location /files/videos {
root /var/www/html/site;
limit_conn addr 1;

location ~ .(flv)$ {
root /var/www/html/site;
limit_conn addr 1;
valid_referers none blocked content.com;
if ($invalid_referer) {
return 403;

I think the above config is enough to identify the issue. please let me
know if you understand about what i am trying to explain.