That is, until they try to jump ahead in the video. If it's a progressive download, they'll be able to fast-forward or skip ahead only as far as the downloaded portion allows them. If a viewer wants to jump ahead in a clip to see if you've included a photo montage, or to see how you handled the reception video, she can't until the entire clip has been downloaded to her computer—which could be minutes if she's on dial-up or trying to access your clips during a time when the network is congested. And if there's one thing you don't want your Web site to do, it's to annoy a potential customer, one who might move on to another videographer's site instead of waiting for your clips to download.
The upside of progressive download is that once the video is downloaded, it will look just as good on a machine with a dial-up connection as it will on a workstation with broadband. The latter customer will just be able to start watching it sooner, although given the fact that Web servers use hypertext transport protocol (HTTP) and transport control protocol (TCP), the client will send a resend request to the server, which takes time and eats up bandwidth. TCP and progressive download technology emphasize accuracy and reliability over speed.
A streaming server takes a different approach to data delivery, with real-time streaming protocol (RTSP) and user datagram protocol (UDP) replacing HTTP and TCP. Larry Bouthillier, director of software development at Harvard Business School, sums it up this way: "The idea behind UDP is that it's better to have a momentary glitch in the audio or video than to stop everything and wait for the missing data to arrive." A streaming server continuously exchanges messages with the player, adjusting to network conditions and letting viewers fast-forward in a clip so that they have to watch only the parts they want to watch.
That results in a better overall experience for the viewer, though a professional videographer may have good reason to want to avoid even a "momentary glitch" in the content. Another quality issue comes into play if you want your clips to be available to dial-up users, since you'll need to encode the dial-up version at a lower bitrate than the broadband version. (Since streaming servers are able to use HTTP/TCP, however, you could split the difference and deliver the broadband clips via streaming and the dial-up versions via progressive download.)
Using a streaming server has other upsides as well, including the fact that it uses bandwidth more efficiently (since it doesn't need to transfer the entire file to a viewer who's only watching a portion of it) and can monitor what clips are being watched and for how long. And streamed video is never cached or saved on a viewer's hard drive, making it tougher for unscrupulous competitors to pirate your work.
So the choice between Web server and streaming server is based on which sacrifices you're willing to live with. The biggest thing the Web route has going for it is that you don't need to change your infrastructure at all; you can start delivering video right away without changing hardware or service providers. In most cases, if you use a streaming server, it won't be your own. There are plenty of streaming video hosting services that offer hosting at reasonable rates—anywhere from around $20 a month for 500MB of storage and 5 gigabits per second data transfer up to around $50 a month for 3GB of storage and 25 gigabits of data transfer—and more and more videographers are taking advantage of them.
One such videographer is Ron Priest of Digital Creations Video Productions in Louisville, Kentucky. His Web site (www.videocrafter.com) is one of the most comprehensive videographer sites I've seen, with a streaming gallery featuring clips from nine weddings, five theatrical productions, a dance recital, and a music video. The clips run anywhere from just a few minutes to close to 20 minutes—an unthinkable length for progressive download.
Digital Creations' gallery includes its own "streaming vs. progressive downloading" section, where he explains why his choice of streaming was a creative as well as a technical one: "To show continuity, the duration of many videos in our gallery is quite extensive," he writes. "We refuse to simply extract a collection of our ‘best shots,' add elegant music, and attempt to dazzle you with fancy transitions and moving backgrounds."
I'm still not convinced that videographers should reject progressive download entirely—for low-bandwidth viewers, it's still a better option, and the one that likely represents the least amount of hassles if you're just making the leap into Web video. But if you want to maximize all that online video has to offer, true streaming's the way to go.