It's confirmed, the first task has been filmed for GoF

Danradcliffe.com has a video of Dan being interviewed by the cartoon network. And he confirms in this interview the first task has definetly been filmed. Apparently, they are currently filming the second task, right now. Also they have another interview with Dan, Rupert and Emma, this article comes from the UK's Young Performer magazine. Note the article is first on the page, you will have to scroll down a bit to find the video.