Xilisoft’s youtube downloader comes with some advanced task management and is a very nice youtube video downloader.
And there is Videora iPod Converter that converts video into mp4 format.
Some more updates:
Found a couple of greasemonkey userscripts for downloading youtube videos. One shows a Download in mp4 format and the other shows a small icon in the task bar which directly opens a download dialogue box when clicked. Apart from that I also found DownloadHelper extension that automatically starts downloading youtube videos that are available in the selected portion of the text in the web page. This almost eliminates the need for Xilisoft youtube video downloader.
The Free Download Manager is good enough and it too eliminates the need for Download Accelerator Plus. What’s more, while DAP opens only 5 simultaneous connections, this one opens 10 simultaneous (or as much possible) which increases the download speed dramatically.
That’s quite some tools. 🙂