Any mod done outside even with original accesoriies will have your warranty voided for that part or parts related to it. That's understood and a common practice with all car companies
So, for the reverse camera mod, what's the worst that could happen? Well, your idrive gets screwed up, no? If that happens, firstly, get the vendor to access the idrive and diagnose for you. If that fails, get him to reverse the mod and then send in to BMW to claim your warranty. Sure, it's a hassle and if it's too much for one, don't even think of any mod during warranty period, period! LOL
Btw, the reverse cam is an officially available option on the F10 and cost $5k - a rip off if you ask me. I could get a 60inch LED TV with change for a home theatre system for that silly price but hey, that's official accesories for you