Canon MARK IV User Manual (en)

Movie Shooting Cautions
About the <E> icon and camera's internal temperature increase
When you shoot movies continuously for a long period or in high 
temperatures, the camera's internal temperature may increase and the 
<E> icon may appear on the screen. Note that if you shoot movies for a 
long period in high temperatures, the <E> icon will appear earlier. Turn 
off the camera when not shooting movies.
If you shoot movies while the <E> icon is displayed, the image quality of 
the movies will not be degraded. However, if you shoot still photos while 
the <E> warning icon is displayed, the image quality of still photos may 
be degraded. You should stop movie shooting and allow the camera to 
rest until the camera's internal temperature decreases.
If movie shooting continues while the <E> warning icon is displayed, the 
camera's internal temperature will further increase and movie shooting 
may stop automatically. Movie shooting will be disabled until the 
camera's internal temperature decreases. Turn off the camera and allow 
the camera to rest for a while.
Playback and TV connection
If the brightness changes greatly during movie shooting, that part might 
look momentarily still when you playback the movie.
If the camera is connected to a TV set with an HDMI cable (p.171), 
pressing the <B> button during movie shooting will not display the 
INFO screen.
If you connect the camera to a TV set (p.170-171) and shoot a movie, 
the TV will not output any sound during the shooting. However, the 
sound will be properly recorded.