I just got a new iPhone. I want to make a video with my fwb.
What kind of video do you want to make?
An amatuer X-rated movie staring me and her.
It isn't right to make a private video without getting permission from the other person on the video.  You should see if it is okay before you film it.
Nah, then it won't be a surprise.
I understand you want to surprise her, but shooting an intimate film of you two without getting her permission could backfire big-time. She might like it, but she might also feel like your violated her trust and never want to see you again. She could also sue you for invasion of privacy -- you better rethink this plan.