I think that your shutter speed is to slow. I don't shoot much video, but I have played with it. My impression is that the video system will take frames at the frame rate AND shutter speed specified. This allows exposures at varying apertures to allow DoF modifications during video. If you are shooting at 1/50 of a second, then the camera may not have time to process the frames at 50fps.

Try increasing your shutter speed to 1/125 then I think you can use a higher video frame rate. Operate in shutter priority or manual mode.

Welcome to NR forum, you are most welcome here, but please be nice to msmoto (and everyone else). She does a great job, and if you just make a civil request of her you will get a huge amount of assistance. Drop her a message if you have an issue, but please give her a chance before you slam her.

We will try this again

Please do a forum search for "D800 video" and place this into the appropriate D800 thread like one of these

http://nikonrumors.com/forum/topic.php?id=5776

http://nikonrumors.com/forum/topic.php?id=3682

http://nikonrumors.com/forum/topic.php?id=2899

And read page 70 of your manual...maybe this is the answer....

Reponed and maybe someone will assist...

Complete noob question but Im not sure how to search for what Im looking either in the manual, menus or online :S
Basically I shoot 1/50 at 1080p 25fps as Im in the UK.
In video live view the D800 shows on the top LCD "A 25 2.8" and Im not sure how to alter that 25 to 50.
Ive hunted the menus and havent found what Im looking for so was wondering if someone could slap me with the simple answer Im not quite getting on my own
Thanks
Rik