The only command I've found is 'demo_max_frames'.
If you would like to record a video at 30 fps you'll need to do the following:
1. Open console
2. Enter 'con_restricted 0'
3. Enter 'fixed_time_step 0.03333'
4. Start recording your video by entering 'capture_frames 1'
5. To stop recording enter 'capture_frames 0'
This will actually save single frames to a folder in your Crysis directory, so you are going to need some space on your HDD

EDIT: the 'video' will be saved to the folder CaptureOutput in your Crysis folder
Oh and around 3 seconds at a resolution of 1655x782 = ~30 MB