I was invited to speak at GDC China in Beijing, so I travelled internationally to speak. The event gave me a free ticket, and I was not paid to speak. My travel and accommodation was fully covered by the event. My employer did not pay my travel expenses, and I used my PTO to speak. It took me 2 days to prepare for my 60 minutes speaking slot, and I had a great time. I'm a man who has been speaking for 15 years. This was a for profit event. Also, It seems that GDC will frequently cover travel costs for good US speakers to fly to China & Europe.