A continuation of my bezier experiments (http://jsdo.it/zz85/o3X1 http://jsdo.it/zz85/k2K0)
This is a closer imitation of the miaumiau's approach to bezier curves. http://www.miaumiau.cat/2010/03/beziers-our-approach/
(site still seems down, but you can read more about bezier curve on http://devmag.org.za/2011/04/05/bzier-curves-a-tutorial/
In this revision, colors are set using hsla. Hue gets rotated with time while the light trails decay in opacity.
Against the black background, the "lighten" global alpha composite mode always work well.
What I'm still not satifisied with is disjoined light segments. I'm not sure if canvas.stroke() can work with differring starting and ending line widths, and in that case, one might have to calculating some normals and use fill() with a custom path to get around it.
In miaumiau's example, a glow filter (available in as3) is probably applied, over here, its imitated with a lighter but fatter line stroke. Also, the point randomness can be expanded beyond the viewport, so as to get a bigger sweeping effect.