I just found this awesome video about dark matter. It is made by Perimeter Institute for Theoretical Physics. The video is very well done and informative, this is probably an understatement. If you are a visual person and have only limited knowledge of physics, then this video may be for you! Ref URL: http://www.perimeterinstitute.ca/Perimeter_Explorations/The_Mystery_of_Dark_Matter/The_Mystery_of_Dark_Matter/
You can start from this embedded video and follow along to go through the whole series of videos.
The video list:
The Dark Matter Mystery: Stars Are Moving Too Fast
The Dark Matter Mystery: 39 Billion Missing Suns
The Dark Matter Mystery: Gravitational Lensing
The Dark Matter Mystery: Most Of The Universe Is Missing