Canon EOS 5D Mark II Video Recording Limits
|All Formats and Frame Rates||30 minutes or 4GB1|
1 If the recording time reaches 29 minutes and 59 seconds or the file size reaches 4GB (whichever occurs first), recording will stop automatically.
- An increase of the camera’s internal temperature may cause recording to stop before the maximum recording time is reached.
Source: Canon EOS 5D Mark II Instruction Manual (English) - page 139