I’m convinced that the single most important factor in implementing a successful Internet video on demand service isn’t selection, video quality, or home theater integration; it’s bandwidth.

YouTube, the most successful Internet video service (at least in terms of overall usage), has gotten it right from the beginning. Their selection is limited to whatever crap users upload and the quality is horrible, but videos begin playing almost instantly and rarely get choppy.

Hulu and Netflix have also gotten this right and are successful despite suffering from a lack of home theater integration options and, in Netflix’s case, a laughably bad selection of content.

However, two players in this field seem to have gotten everything right except the bandwidth issue. Microsoft’s Xbox Live video service and Sony’s new PlayStation 3 video store both offer an excellent selection of recent movies and TV shows, many of them in gorgeous HD with Dolby Digital 5.1 audio, but both services suffer greatly from limited bandwidth.

On Xbox Live, videos often download fast enough to be watchable as long as you don’t mind waiting five to fifteen minutes before you can actually start the video. Occasionally, though, the service seems to fall flat on its face and you’ll be forced to wait an hour or more before you can start watching. Not exactly convenient when you just want to plop down on the couch with your dinner after a long day and watch a movie, but at least it doesn’t happen too often.

The just-launched PlayStation 3 video store is, in my experience, far worse. Like Xbox Live, it’s unable to even come close to taking advantage of my available bandwidth, but unlike Xbox Live, it tries to pretend that this isn’t an issue by allowing me to start watching the video instantly. Every so often the audio cuts out, then a moment or two later the video pauses (yes, in that order), and I’m forced to wait while the bytes trickle slowly in and the buffer fills back up. Then I have to manually rewind to the point where the audio cut out to hear what I missed.

Last night it took nearly an hour for the PS3 to download a half-hour standard definition TV episode (about 350MB) that cost me $1.99. The same episode is available for free on Hulu at the same quality and without the bandwidth problems. If I were less scrupulous (and I often am) I could download it from Usenet in about four minutes flat, since my Usenet provider doesn’t seem to have any problem saturating my bandwidth.

The astonishing thing about this is that bandwidth is ridiculously cheap these days. It’s surprising that Microsoft and Sony are allowing their otherwise excellent on-demand video services to suffer by ignoring such a basic component.