underexposing = more data to work with?

[perhaps]

i found an interview with dod mantle of 28 days later, and caught this snippet..

"Dod Mantle shot as wide open as possible with ND filters to minimize DV's seemingly infinite depth of field, and he underexposed by one to two stops to get more information on tape. (The XL1 has an exposure value of about 320 ASA without altering the shutter speed.) "

i know the XL1 and DVX are two different cameras, but does this apply to it as well? does underexposing the footage a bit benefit with extra visual data to work with in post? this would be great to know, as i prefer to color correct and retouch my footage intensely as i do with my RAW photographs.. and the more data, the better!

 

[Scottdvx100]

No. You want to use as much of the dynamic range as possible. Lean toward under-exposing just to avoid clipping that happens when going too bright.
When the image is digitized ,assuming 256 values, if you under-exposed by a stop of linear then you're cutting your data in half.

 

[Barry_Green]

In general underexposing is preferable to overexposing in video, because video retains shadow detail better than it can hold highlight detail. But you usually wouldn't underexpose if you don't have to; Mr. Mantle was probably forced into it to try to retain sky detail that would otherwise blow out.

One thing that underexposing does for you is it increases color saturation, so I do sometimes bias towards a half-stop of underexposure just for that. But you normally would want to expose as accurately as possible, unless you're having issues holding the dynamic range of a scene (like 28 Days Later would).