媒体吹风会 (Méitǐ chuīfēng huì) is similar to a press conference but it is a less formal version. The atmosphere of the interview can be more relaxed but equally detailed. Another commonly used phrase is 新闻吹风会 (xin wen chui feng hui).
媒体 actually refers to media. 新闻 refers to news.
The interesting part is actually '吹风会'. If you translate it literally, 吹 is blow; 风 is wind; 会 is gathering/conference --> so it means blowing wind gathering/conference. In a way, blowing wind can mean to be how news spread, like the wind. Therefore, in a way, from the words alone, you are able to guess the meaning of the words.
So when do you usually use this?
This is commonly used when there is a new policy that might be controversial or garner a lot of feedback. In a way, they would release it in a more relaxed and tidbit-sized manner to first gauge the reaction of the public to the news, as well as a way to prepare the public for the news and act accordingly from there.