Personally I RoF invade and get invaded all the time. This is no offense between you or anyone, but, again, there is a difference between pvp being broken and being pvping with no skill. The invader probably had little skill as well since he ran up to face the person and casted a spell that immediately gives away his position and clearly marks him with the red hand. It would have been easy in that situation to roll past the flame towards the hand and (the sword was long enough) swipe the caster. If 'you' (the proverbial you, not you personally) have any experience with the fire skills you'll know that every one of them are easily rolled away from and most have a long charge up(as said in the video comments).

Anyone who sees a pyromancer spark up and turns to block it is going to have a tough time with pvp RoF or no. That doesnt prove pvp is broken, it proves that the host had zero skill and didnt belong running around the forest with 90k souls and 10 humanity in human form. Although I will grant you that RoF is arguably overpowered under certain situations (mainly extremely low sl levels getting it twinked).

Dark souls rusty iron ring