Adding .mov files (not from YouTube) [duplicate]

You can use upload_mimes filter and add mime for .mov files (video/quicktime).

add_filter( 'upload_mimes', 'customizeMimeTypes', 10, 1 );
function customizeMimeTypes( $mimeTypes) {
    $mimeTypes['mov'] = 'video/quicktime';
    return $mimeTypes;
}

If you want to embed video with media library you can use wp_video_extensions filter.

add_filter( 'wp_video_extensions', 'addMovToWPVideo');
function addMovToWPVideo( $extensions ) {
    $extensions [] = 'mov';
    return $extensions ;
}

More info:

https://developer.wordpress.org/reference/hooks/wp_video_extensions/
https://codex.wordpress.org/Plugin_API/Filter_Reference/upload_mimes

Hope this helps you!

Note: check php max upload file size in php.ini too!