All Youtube videos contain miniature windows of disruptive content

Hi, as the title suggests, I have just come across a problem where any youtube video I try to play goes as follows:

The video plays normally, but with a small window that appears in the top left of the video of interest. The small window plays a looping video of MoistCritical screaming "woooo!".

I am not tech savvy, so can someone explain to me what is happening? Is this evidence of malware on my PC? I use windows defender …

goes interest malware play problem try video videos window windows youtube