Well, trying to use this myself, and found two things...
1. If you're on a development machine, you need to add 2 lines to the curl_setopt settings in the galevents.class.php file (core/components/gcalevents/model/gcalevents)
2. You need to change line 224 from this
$this->url = str_replace('{{agendaID}}', $this->c['agendaID'], $this->url);
to this
$this->url = str_replace('{{agendaID}}', $this->c['userID'], $this->url);
The snippet call uses 'userID' but the class has 'agendaID'.
I can now get the title to extract but nothing else!!