If the church remains fairly unchanging over time, and communicates their stance, you can't really blame them because "they're medieval". Blame yourself for choosing something medieval. Or better yet, rent an abandoned church and dress Uncle Festus up like a minister. The cameras won't know the difference. You could even talk him into wearing a GoPro on his head.
There's a lot of abandoned churches around here now that are maintained for the sole purpose of being non-denominational wedding venues.
I guess that's the benefit of not having a church, I can choose an officiant I know will follow what I want in a wedding, not what the church has been doing for centuries.
I like your GoPro idea. I'll definitely pitch this to my fiancé. That said, GoPros in some of the bridesmaids' and bride's (ninja edit to add) bouquets are definitely happening at my wedding.