Still confuse on how to download a Youtube video? and anything? Haha. First of all, you must download Free Download Manager (FDM). FDM is a download manager that supports resumable downloads and multiple simultaneous downloads. You can choose between regular FDM or FDM Lite. FDM Lite contain only download manager program without any plugins. Regular FDM includes video conversion plugin, bittorent plugin, uploads plugin and language pack. After download, install it.
Next, open your browser (i.e. Mozilla Firefox). Go to Youtube.com or any web you wish. Right click the video title and click Download with Free Download Manager.
Decide where you want to save downloaded video. OK.
Besides download video, if you download a zip file, FDM gives you option to preview the zip files before download them. Even you don't assign FDM to download something, if you let FDM start on Windows startup, it will take over your downloading action because it is able to monitor any download activities.
You now can download Youtube video directly from the site by clicking on Download MP4 button. Go to My Videos -> Uploaded Videos.
Picture taken from labnol.org. Anyway, you can still use Free Download Manager to boost your download speed.