The Science of YouTube: Lightning

I think theres at least one problem with the comments in the video:
"You can see the step leader as a purple tunnel around the bolt"

I'm not an expert on lighting, so I might be wrong here...however, I am extremely knowledgeable on photography and optics. The purple you are seeing there is almost certainly chromatic aberration (sometimes called purple fringing). When you have a lens, it bends the light that passes through it. However, it is currently impossible (and perhaps not even theoretically impossible, but I wouldn't know) to make a perfect lens. Due to the imperfection, different frequencies of light get bent to a different degree. Think of it like a prism, but to a much smaller degree.

Normally, this defect isn't very noticeable at all. However, when you get a very strong and sharp contrast (like taking a photo of a shadowed tree with the sun behind it) the problem is greatly exaggerated and you start to see the colors show up (purple is most common, but you can occasionally get other colors). In the case of lightening, you also have an extreme contrast between the bolt and the background. When you buy very expensive lenses, they do a much better job of dealing with this. However, the lower quality lenses (like you are likely to find on a consumer camcorder) are very susceptible to this.

http://en.wikipedia.org/wiki/Chromatic_aberration

In optics, chromatic aberration is caused by a lens having a different refractive index for different wavelengths of light (the dispersion of the lens).

Longitudinal and lateral chromatic aberration of a lens is seen as "fringes" of color around the image, because each color in the optical spectrum cannot be focused at a single common point on the optical axis.

Since the focal length f of a lens is dependent on the refractive index n, different wavelengths of light will be focused on different positions. Chromatic aberration can be both longitudinal, in that different wavelengths are focused at a different distance from the lens; and transverse or lateral, in that different wavelengths are focused at different positions in the focal plane (because the magnification of the lens also varies with wavelength).

I don't have a lightning storm to go double check with, but I'm pretty sure you can see the purple with the naked eye too.

O.O ooh!!! lightning!!!! sparky, shocky, and electrically

O.O ouch.

lol @ ending.

LIGHTNING BOLT. LIGHTNING BOLT.

I live in a country with a lot of lightning. I've personally never seen a purple colour. Personally I don't think I'll try to find it. Its way too bright to distinguish any colour in there.

As for the video i think the real question is the step leader on the outside. I don't think anyone can actually see it. without slow motion video at least.

I HAVE THE POWER!!!!!!!!!!!!!!!!!!