Mac OS 7.6 installs the Apple Video Player application and the Video Startup extension. The Video Startup extension is not compatible with the TV Setup control panel used to control the TV functions on the Macintosh TV. Either deselect the Video Startup extension in the Extensions Manager control panel, or drag Video Startup from the Extensions folder to the Trash.
The Macintosh TV does not need the Apple Video Player or Video Startup extension. The Apple Video Player may also be dragged to the Trash from the Apple Extras folder.