If you're doing professional video you need the ability to capture ANALOG video sources. Especially if you're doing live switching. Even a show like Rachel Ray actually uses "higer end" Pro-sumer video cameras and they switch of those cameras as sources.
Many of us use the ANALOG inputs as there's a latency issue using firewire for a switch so you'd need higher end cameras with SDI.
Betacam SP is still widely used. Like any pro you need many tools to get the job done. To infer that everyone is totally digital is not correct. We DO digitize the video once then from that point on it remains digital as a AVI or Quictime file or back to any of the flavors of Digital tape.
Once I was done with my flyer projects I'd capture it via a G4 mac with Final cut using an addon YC card or just save it out to a mini-DV deck.
All this talk about Amigas and video will have me lug in my A1200 to demo for students who don't understand what interlace flicker is, NTSC or HD to them it's either TV or computer monitor. Once I show them the NTSC flickering workbench screen they'll get the whole scanline NTSC thing. If they're good I'll let them play Super Stardust.