Hi Pauro, here is dirty add for category excluding from Time Machine results.

Find line 250 in time-machine.php and replace next code:

foreach ( $r as $post )
{
	// prepare excerpt
	if ( $tm_excerpt == TRUE ) {
		$tm_post_excerpt   = $post->post_excerpt;
		if ( $tm_excerpt_cut == TRUE ) {
			if ( $tm_excerpt_length && mb_strlen($tm_post_excerpt) > ($tm_excerpt_length+1) ) { $tm_post_excerpt = tm_substr_utf8($tm_post_excerpt, 0, $tm_excerpt_length)."…"; }
		}
	}

	// print formated post line
	if ( $options['display_commentnum'] == "1" ) { $pcount = ' (<span title="'.__("Number of comments", "tm").'">'.$post->comment_count.'</span>)'; } else { $pcount = ""; }
	echo '<li>'.substr($post->post_date,0,4).': <a href="'.get_permalink($post- rel="nofollow">ID).'" title="'.__("Published at", "tm").' '.$post->post_date.'">'.$post->post_title.'</a>'.$pcount.' '.$tm_excerpt_before.$tm_post_excerpt.$tm_excerpt_after.'</li>';
}

with this code:

foreach ( $r as $post )
{
	$pcats = get_the_category($post->ID);
	$no_this = 0;
	foreach ($pcats as $pcat) {
		if ( preg_match("/(5|2)/", $pcat->cat_ID) ) { $no_this = 1; }
	}
	if ($no_this <> 1) {

		// prepare excerpt
		if ( $tm_excerpt == TRUE ) {
			$tm_post_excerpt   = $post->post_excerpt;
			if ( $tm_excerpt_cut == TRUE ) {
				if ( $tm_excerpt_length && mb_strlen($tm_post_excerpt) > ($tm_excerpt_length+1) ) { $tm_post_excerpt = tm_substr_utf8($tm_post_excerpt, 0, $tm_excerpt_length)."…"; }
			}
		}
				
		// print formated post line
		if ( $options['display_commentnum'] == "1" ) { $pcount = ' (<span title="'.__("Number of comments", "tm").'">'.$post->comment_count.'</span>)'; } else { $pcount = ""; }
		echo '<li>'.substr($post->post_date,0,4).': <a href="'.get_permalink($post- rel="nofollow">ID).'" title="'.__("Published at", "tm").' '.$post->post_date.'">'.$post->post_title.'</a>'.$pcount.' '.$tm_excerpt_before.$tm_post_excerpt.$tm_excerpt_after.'</li>';

	} //no_this
}

And you need to replace 5|2 with category ID’s you wish to exclude separated with pipe sign.

I have just post a new thread in wp forum titled „excluding post from certain category“.
please take a look, and hopefully you can help me here.

(I wonder should I post the question here?)

Thanks