The above YouTube video is one of the series of videos uploaded by the Nobel Prize Foundation into their YouTube channel where Albert Fert answers questions made by many different persons (I have even seen one Second Life avatar asking one in one of the videos). The series can be watched: Answers from Alber Fert.
Albert Fert won the Nobel Prize of Physics in 2007, together with Peter Gruenberg, for the discovery og the Giant Magnetoresitance (GMR) effect in 1988, which he explains in a very simplified way in the above embedded video. The Nobel Prize website is quite good and you can find not only a lot of information about him in the 2007 Physics Prize page but also a downloadable video with his Nobel Prize Lecture.
GMR is the effect of decreasing of the electric resistance of a material in the presence of a magnetic field. It's giant because the resistivity can drop up to 80%. The effect is very well explained in the Wikipedia article linked above and by Albert Fert itself in the videos (in particular the one I put in this post). It is used comercially in read heads of hard disk drives, this being actually the application that made this discovery so important.