iptables rule for ssh port forwarding

I'm using a program that streams video using both UDP packets for data and
TCP for control,i want to ssh the tcp data but if I do an ssh tunnel and I
put localhost as destination in my video streaming software,the tcp
handshaking is ok but then also the UDP data is sent to localhost and I
don't want that! So I was thinking about an iptables rule (after having
created the ssh tunnel) that sends all the tcp packets directed to a certain
port(the video client's port ),to my localhost instead of the real
destination,in this way the videostreaming software would send the udp
packets to the correct address and the tcp packets to the encrypted
tunnel... what would be this rule?