Never used it but its in the manual that it can be done.

Unlike some things that record dual link the HDCAM SR records both signals in full 4:2:2 while some dual link solutions record one 4:2:2 and then a 0:2:2 signal.

It can be used for seperate camers in 4:2:2 modes but they have to be syncronized in order to record if I'm not mistaken.

Plenty of people have been getting great results keying HDV using my software, dvmatte blast. (http://www.dvgarage.com)

It works for Motion (and eventually, FCP), and renders in realtime.

Check it out!

your advices are very useful. Thanks again to all you.