How to set effect on video?

How can I record light trails in video?

• Hello all, I'm a photographer and I like to shoot long exposure light trails. I have seen a similar effect used on videos, but I can't figure out how to get the software to apply this effect. I assume that somehow you set a luminance tolerance, and if the light is of a certain brightness, the pixels from that frame are carried over to the next frame and so on. Does anyone have any information on how to do this? And is there a less advanced software that can do this. I'm more familiar with photoshop than video editing. Example of the basic technique. http://www.youtube.com/watch?v=jEWHY2PrXl0

• Answer:

  The link you give is NOT an example of long exposure light trails - it is a computer animation of a slow moving light path generated by software This link http://www.youtube.com/watch?feature=endscreen&NR=1&v=OC564dRMO1M that came up after that one appears to be true light trails and is a lot trickier to explain because the light source is over exposing its path even though the room is not brightly exposed and sunlight is streaming in the window. Notice the varying width of the light blobs and the varying speed of movement. Your explanation is possible, but the basic trails are going to have to come from relatively slow exposures rather than snap shots and persistence of the eye.