LABEL YOUR VIDEOS, PLEASE!! I hate having to actually watch them to find out what they are. Hearts on Fire is definitely the first thing that came to mind when I read the topic. The OP is pretty boring, besides the ending, which definitely is incredibly fucking epic and makes up for the other 5 minutes.
Within Temptation - Ice Queen
I dunno what genre you'd call these guys, but they definitely have a ton of songs about fantasy crap and a lot of annoying overblown faux-orchestration and stuff ala power metal bands, so I will call them that. This gets my vote for most hilarious metal video ever, even though it's nowhere near as conceptually ridiculous as the ones with plots or the ones with guys with swords running around the woods and blowing up the moon. Just something about how incredibly not hardcore the music is and how serious the male performers are taking it makes me lol every time, case in point being the firebreathing guitarist during the accapella interlude. The high point is definitely the guitarist's epic metal maneuver at 3:20. "YEAH, I'M GOING TO ROCK THIS SHIT WITH MY FUCKING CLAW!"