I like to use a simple program like Tubetv. just insert the url and click save. It converts it into many formats. Funny thing is it works on more than the websites it lists as working with. Give it a shot. Apologies if someone has said this I'm new to DP and just getting the hang of all this.
It looks like keepvid.com is the most popular website for downloading youtube videos. If you need to convert the video file to mpg or wmv, you can download a mozilla firefox add-on called "DownloadHelper" which has this ability.
I use this site to do that http://www.downloadyoutubemp3.com/. There are also programs that do this job. So yes it is possible.
Go to the YouTube video page and copy the URL of the video you wish to save. Once address has been copied, visit SaveVid and paste that URL into the URL text field, then click the Submit or Download button. If done properly, the page should open a new window or display a link to each of the video formats that can be saved. Savevid will give you the option to save the video as FLV, 3GP, MP4 and WebM format. If you're wanting to watch this video on the computer i recommend saving the video as MP4 format.
By a Youtube downloader,the one I have used for long can not only download videos from youtube but also convert the videos to the right format you need.
I use the DownloadHelper addon for firefox. Works like a charm. Not only for youtube videos, it works for any website where there's video, audio or picture galleries.
I have an IDM. So, Whenever I play a youtube Video it gives me the option to download that video..Straight forward and easy.