Canon EOS 80D Instruction Manual page 489

The ISO speed cannot be set for movie shooting.
In shooting modes other than <a>, the ISO speed is set

automatically. In the <a> mode, you can freely set the ISO speed
(p.299).
The manually set ISO speed changes when
switching to movie shooting.
ISO speed will be set according to the setting for [Range for stills]

during viewfinder shooting and Live View shooting, or that for [Range
for movies] during movie shooting with manual exposure.
The exposure changes during movie shooting.
If you change the shutter speed or aperture during movie shooting, the

changes in the exposure may be recorded.
Zooming the lens during movie shooting may cause changes in the

exposure regardless of whether the lens's maximum aperture changes
or not. The changes in the exposure may be recorded as a result.
The subject looks distorted during movie shooting.
If you move the camera to the left or right quickly or shoot a moving

subject, the image may look distorted. The problem may be more
noticeable in time-lapse movie shooting.
The image flickers or horizontal stripes appear
during movie shooting.
Flickering, horizontal stripes (noise), or irregular exposures can be

caused by fluorescent lighting, LED lighting, or other light sources
during movie shooting. Also, changes in the exposure (brightness) or
color tone may be recorded. In the <a> mode, a slow shutter speed
may reduce the problem. The problem may be more noticeable in
time-lapse movie shooting.
Troubleshooting Guide
489