Canon EOS Rebel T1i Instruction Manual page 206

Troubleshooting Guide
The camera makes a noise when it is shaken.
The built-in flash's pop-up mechanism moves slightly. This is normal.
The shutter makes two shooting sounds during Live View
shooting.
If you use flash or if ISO 3200 or higher is set, the shutter will make
two sounds each time you shoot (p.107).
The movie shooting terminates by itself.
If the card's writing speed is slow, movie shooting may stop
automatically. Use an SD Speed Class 6 "
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 recording time
reaches 29 min. 59 sec., movie shooting will stop automatically.
The 1920x1080 movie looks distorted.
When shooting movies at 1920x1080 with this camera, only 20 frames
are recorded per second (20 fps). Therefore, if there is fast movement
in the movie scene, the picture might look distorted. This distortion will
be resolved if you shoot at the 1280x720 recording size (p.123).
When the movie is played, camera operation noise can be
heard.
If you operate the camera's dial or lens during movie shooting, the
respective operation noise will also be recorded (p.127).
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" or faster card. To