Apple Video System - Manual (Page 28)

7 Locate the video-in access cover on one side of the vertical
plate attached to the logic board. Remove the cover from
this opening by squeezing together the plastic tabs that hold
it in place.
Note: Your logic board may not look exactly like the one
pictured here, but the video-in slot and access cover are in
the same position regardless of the logic board you have.
Video-in slot Vertical plate
Plastic tabs
The plastic access cover is on the
other side of the vertical plate.
Metal retainer
22 Chapter 1