If you just want to see Vanaduke and not the full Firestorm Castle run, it starts at about 49 minutes.
Here's the video: http://www.justin.tv/madcap7331/b/284508578
Quality is about the best I could get it at without suffering lag, unfortunately.
It'll be deleted soon enough because of music and such. So catch it while you can!
I'm not a forum lurker, but I'll try to answer any questions.
Some advice!
While in the Citadel, you were trying far far far too hard to always melee. I think this is because you brought one of the worst guns in the game with you. The Argent is, in every way, better than Sentenza. You'll need to know when to move back and shoot the slags instead of running up and wacking them (see: firebreath).
As for Vanaduke, when you have his aggro, do not ever NEVER EVER! think moving back slightly or just blocking and holding still is a good idea. Always, always strafe around him so he takes longer to attack, and when he does it's more likely to miss, and never double back while strafing unless you hit a wall, but if you go back the way you came and don't prance around a little, then he should just blatantly miss and toss himself/mace a corner.
Long and short, you block too much instead of moving.