Canon EOS Rebel T4i 18-135mm IS STM Lens Kit Instruction Manual page 329

Playback Problems
Part of the image blinks in black.
It is the highlight alert (p.268). Overexposed highlight areas with a loss
of highlight detail will blink.
The image cannot be erased.
If the image is protected, it cannot be erased (p.262).
The movie cannot be played back.
Movies edited with a personal computer using the provided
ImageBrowser EX (p.350) or other software cannot be played back
with the camera. However, video snapshot albums edited with EOS
Video Snapshot Task (p.190) can be played back on the camera.
When the movie is played back, camera operation noise
can be heard.
If you operate the camera's dials or lens during movie shooting, the
operation noise will also be recorded. Using an external microphone
(commercially available) is recommended (p.193).
The movie has still moments.
During autoexposure movie shooting, if there is a drastic change in the
exposure level, the recording will stop momentarily until the brightness
stabilizes. If this happens, shoot with <a> shooting mode (p.173).
No image appears on the TV screen.
Make sure the stereo AV cable or HDMI cable's plug is inserted all the
way in (p.258, 261).
Set the video OUT system (NTSC/PAL) to the same video system as
the TV set (p.261).
Troubleshooting Guide
329