YouTube succeeded where Google Video didn’t because users were able to see their videos posted immediately, says Google’s Marissa Mayer.

Google Video, on the other hand, can make viewers wait anywhere from two to four days for the video to be vetted and posted for public consumption.

Editorial, eh. It just doesn’t scale.

Other interesting bits:

• The reason Google sets the default at 10 results on the first page is that having more results slows down the display time, resulting in less searches overall.
• The key motivator for Google developing Gmail in AJAX was speed.
• Mobile devices suffer from slow data transfer, and it takes too long to input data and interact with Web applications on the devices.