yes you can.... i have usb streaming on my dv cam but it's rubbish so i use the dv port (firewire), that pretty much every dv camera has, directly into my computer... now you can use this directly sometimes, but on mine it zooms in on the pic by default... so i use trackercam software available from
http://www.trackercam.com/TCamWeb/download.htm and then set that software as my "webcam"