Orbit Downloader, leader of download manager revolution, is devoted to new generation web (web2.0) downloading, such as video/music/files from Myspace, YouTube, Imeem, Pandora, Rapidshare. And to make general downloading easier and faster.
The most likely reasons are:
You have not choose Tools-Enable 'GetIt' button for catching media.
Or you use firefox, there is a grey button on the top right corner of the video. It's a small Orbit LOGO. You can click it to download the video instead of 'GetIt' button.