you already have that firewall. it's your experiences and human connections, your understanding of media, your personal history and learning and the feelings you experience.
you don't need a firewall to keep you from being manipulated, you need to learn to fucking read and think and feel. to learn and question, to develop trusted friends and family you can talk to.
if it feels like your emotional backdoors are being exploited then maybe youre thinking or behaving like a monster and your mind is revolting against itself.
Do you still have the video link???