eyepiece cover
 

I am just getting used to my 5D and DSLR's in general. My question is around the eyepiece cover. The manual says it's to be used when the camera is not held up to your eye, as the exposure could be wrong. I am thinking that with the mirror locked up, as in movie mode, there is no need for the cover. Is this correct?

I don't honestly know, but I would bet there is still light leaking issues with the mirror up. HOWEVER, that's more of a long exposure (think bulb) type of issue as far as I know. At any sort of video-like shutter speeds, this is a non-issue. Also, you're probably shooting in manual anyway, so the meter doesn't mean much (blinkies/RGB sure, metering, not so much).

I agree with Bill. The warning is mostly about the autoexposure meter (silicon photocell) that is behind the focusing screen. When the mirror is up, like when in movie mode, that meter is not used at all (because it doesn't get any light). In that scenario, the only benefit to covering the eyepiece would be prevent light leaks, if any exist, but that would only be an issue for long exposures.

Tested
 

I did a quick test this afternoon just to confirm. Putting the eyepiece on made no difference, either to the exposure level indicator of the finished product ( AVCHD Blu Ray on SD DVD) .
I am a little confused about what the exposure level indicator is telling me. I have ben going half way with the shutter button to get an exposure reading, then changing the aperture to get it right before shooting.
Once I am rolling, is the exposure meter telling me where I am in reference to a standard exposure relative to the setting I started with, or is this somehow a true reading of exposure relative to standard for the current scene?