How does this internet adv. load so fast on my slow connection?

I have a 56k modem. It takes a long time (20-30 seconds) to load regular graphic rich webpages. It is virtually impossible to watch streaming video from any source (local newspaper and television station station sites for example). It takes me a very long time to download a 30 second video clip.
However, when I clicked on a story on, a 20 second, 3/4 of my screen, relatively clear, commercial for Mountain Dew popped up on my computer almost instantly. It looked really good. How did they do that? Where did it come from? If it helps, here is the beginning of the URL: followed by a string of 100 or so numbers and letters with a couple of “” thrown in.

If I remember correctly, Unicast invisibly loads the video in the background while you’re reading the page. The video doesn’t start playing until it’s already fully downloaded.

Here are some Slashdot stories about them, if you’re interested:
New Ultra-Intrusive Pop-up Ads Introduced
Commercials Come To The Net (After This Word
Unicast Claims Success With Internet Commercials

Was the ‘commercial’ full-motion video, or was it animation? If it’s 20 seconds long and occupied 3/4 of your screen, it was probably Flash animation, which requires much less data than MPEG-type video. To look reasonably sharp at 3/4 of your screen resolution, a 20-second MPEG clip would require several megabytes of data, and a 56k modem user would probably leave the website before the clip finished downloading. (Not to mention you’d lose much of your bandwidth.) A similar Flash clip would probably be about the same size as the webpage itself, so it would finish downloading and begin playing only a short time after the page finished loading.

I can confirm Reply’s correct assertions. I’ve bought Unicast Superstitial ads in the past and that’s one of their big selling points - they don’t hold up page downloads. A Java app initiates a “polite download” as you’re surfing a Unicast-enabled site. Another app called “TransitionSensor” makes note of when you’re moving from page to page within that site. If the ad is finished downloading when you click to another page within the website, it will trigger and play.

Most fast loading animations use Flash animation and Flash files are able to use a very small amount of bandwidth because they use vector graphics. That means instead of storing the color of every pixel, the files store the coordinates of shapes and the color for the whole shape. It’s more complex than that but it means a full page advertisement can download in seconds if the color and shapes are simple.
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It’s full motion video, not Flash/vector animation. Unicast just caches the entire movie before playing it.