Canon EOS 5D Instruction Manual page 227

Live View shooting is not possible.
For Live View shooting, use a memory card (a hard disk-type card is not
recommended). A hard disk-type card requires a lower temperature
range for operation than normal memory cards. If the temperature gets
too high, the Live View shooting may stop temporarily to prevent damage
to the card's hard disk. When the camera's internal temperature
decreases, you can resume Live View shooting (p.123).
I cannot take still photos at the shutter speed, aperture or ISO
speed I set during Live View shooting.
Set [Screen settings] to [Stills display] or [Exposure simulation]
(p.109).
Movie shooting terminates by itself.
If the card's writing speed is slow, movie shooting may stop
automatically. Use a card with a read/write speed of at least 8 MB per
sec. To find out the card's read/write speed, see the card
manufacturer's Web site.
If the movie file size reaches 4 GB or if the movie is shot for 29 min. 59
sec., the movie shooting will stop automatically.
Movies cannot be shot with manual exposure.
Set [LV func. setting] to [Stills+movie], set [Screen settings] to
[Movie display] (p.126), and set the Mode Dial to <a>.
The ISO speed cannot be set when shooting movies.
When the shooting mode is set to <1/C/d/s/f/F>, the ISO
speed will be set automatically. You can set the ISO speed manually in
the <a> mode (p.131).
Troubleshooting Guide
227