This should work:
function max_video_size( $file ) {
$size = $file['size'];
$size = $size / 1024;
$type = $file['type'];
$is_image = strpos( $type, 'video' ) !== false;
$limit = 750;
$limit_output="750kb";
if ( $is_image && $size > $limit ) {
$file['error'] = 'Video files must be smaller than ' . $limit_output;
}
return $file;
}
add_filter( 'wp_handle_upload_prefilter', 'max_video_size' );
Rinse and repeat, changing video in the $is_image line to whatever filetype you want to specify, and even by altering the function, building all desired filetypes into the one filter.
FULL DISCLOSURE = the core of this answer is found in Set limit to media upload?