To add YouTube to a post, use the shortcode “embed” youtube URL “/embed” (tags in square brackets)
To add a poll to a post, add a poll in the “Polls->Add Poll” Dashboard item. Note the poll ID. Then link to it in a Post with the shortcode “poll id=the_poll_number” in square brackets (where the_poll_number is the number defined in the dashboard).
Another cool thing is the page break. Check this out: