Steps to get the HTML

1. Login to Facebook
2. Visit Facebook's events page
3. Scroll to the bottom of the page till you have birthdays from all the months
4. Right click on Today's Birthday or Upcoming Birthdays
5. Select Inspect from the dropdown
6. In html inspector right click on div with id="birthdays_content" and select "copy" > "Copy element"
   
7. Paste the content in the textarea and click Process
8. Import the birthdays.csv generated by the site to Google Calendar