My Portal for HoloLens video has received a copyright claim by Nerdist?

Not too long ago I posted a video about my fan Portal game for the HoloLens and today I received a youtube copyright claim email by 'Nerdist' who claims 'visual content' on my video. The video was recorded by me and the content within the video doesn't contain anything related to their channel or company. The music within the video was from the video game 'Portal 2' to which I have credited. But again, I don't understand how this has anything to do with Nerdist.

The video is now blocked due their claim. Blocked Video

Here's the gif showing a short clip of the blocked video : https://gfycat.com/PlumpLankyIsabellinewheatear

Can I dispute this claim? I understand the use of the game's soundtrack, but the claim is for the visual content which isn't owned by Nerdist.

Thanks guys

EDIT: It's been resolved, thank you everyone for your support. I love this community