I don't mean to be annoying but I've found a slight problem using Ant video downloader and I thought I should explain how and why. It's not that Ant has a problem, let me try explain...
To download some videos with Ant you end up downloading them twice, I guess for most people - without really knowing it. For example, when trying to download a flash video from a video streaming site without clicking on a download button/link on the web page itself (if it has one), I have to click on the play button on the video player on the web page, before Ant will download or offer to download the video. This means that the video is downloaded twice because, the video is eventually fully downloaded whilst it is playing (same if you press play and then pause) for several websites I've tried (unless it only loads a little bit like on YouTube) and Ant video downloader then/also downloads it into the Downloads folder (or other destination folder you chose) when you tell Ant to download the video. Not really a problem if you have fast broadband with an unlimited download contract but living where I do, it doubles the amount of data downloaded which means it annoyingly takes twice as long to download, than compared to just streaming it without using Ant to download it. Although, maybe some websites don't require the play button to be clicked before you can use Ant?
In Windows using Firefox, the streaming flash video is downloaded as a .tmp file which I manually have to rename to .flv once I have used something like HoboCopy to rip it from the temporary folder. The destination folder on my PC for most flash streaming videos when you click the play button is C:\Users\Username\AppData\Local\Temp\acro_rd_dir Sometimes I have to click refresh in that folder to show the true or current file size, also I choose to show hidden folders to be able to navigate to that folder, that is if I don't want to copy & paste that C:\... address into my folder browser (Windows Explorer). Remember to replace Username with your computer username. I'm not sure exactly where the flash video gets downloaded to with Firefox in Ubuntu (I guess you can find an answer to that pretty easily).
Hope that makes sense, was quite difficult to explain :)