There's no need to turn the rules off and on. Just make a rule specific to the particular server:
# host flash.media.israelnn.com
flash.media.israelnn.com has address 208.116.54.54
# iptables -t nat -A OUTPUT -p tcp -d 208.116.54.54 --dport 80 -m owner \! --uid-owner proxy -j REDIRECT --to-ports 1935
And no, this example isn't in the README file. Examples are only there to point you in the right direction. You're expected to know how to read your system documentation and figure out the rest.
This particular server is just using plain RTMP. Just use
Wireshark/tcpdump to extract the play parameters. It's also using the Red5 RTMP server, which doesn't send a "Genuine Adobe" handshake. I've got a workaround for that, but the session will still fail because the server sends a response that the Flash client doesn't like.