Changing positions after praying a Fardh prayer in order to pray a Sunnah prayer

[bachamazar]

You know sometimes when you're in the Masjid and you've just finished praying a Fardh salaah, you notice people around you moving to different parts of the Masjid in order to pray their Sunnah. Have you ever wondered why?

[video=youtube;K4V3u-J5i1s]http://www.youtube.com/watch?v=K4V3u-J5i1s[/video]