Guys, dont forget the Xiaomi Yi does not include any cooling fan in it. Ofcourse the Yi can get hot because it has to record and save at the same time. Next to that, 1080p 60fps recording drives the Ambarella chip to work hard. And when using scripts it even has to work more harder. That its getting hot isnt a really big issue. It probably will shutdown itself once it reached the max. temperature.
If you record on 1080p 60fps (and 35Mbps) the Ambarella chip gets warm (ofcourse it get warm). Beyond that, if you use the WiFi module aswell it even produces more heat inside the small housing. The heat cant get out easily aswell, so the heat will be stuck inside. Also, dont forget the small LEDs are getting VERY hot aswell. I noticed that once I had to change the focus of the Yi. After 2 minutes the LEDs were hot already. In the Xiaomi Yi app there was an option to turn them off.