Things like YouTube videos, Google Calendars and Google Maps can be added to your site from the Insert pane.

YouTube

You can change the YouTube embed settings by clicking the gear icon above the video or by selecting the embedded video and hitting Enter.

Google Calendar

Be sure the calendar you embed is shared correctly. Once embedded, access the calendar settings (hover over calendar and click the gear or select the calendar and hit Enter) to change how the calendar looks on the page.

Google Maps

Create a map by inserting an address or access maps you have in Drive by selecting My Maps. If you add a Map from Drive, be sure that it is shared properly.