While searching wowhead.com i found a very very informative show which has real gameplay at very good quality of most of the raids and instances we use today including Naxx.
As it was posted in the guild info notes it would be very good if you were to take time to learn the fights this program should help you. Its called Project Lore. It shows trash fights and most important the boss fights and explains what the bosses will do and they give some strategies to take them down. just follow the link of course and watch away to learn. ENJOY!
http://www.wowhead.com/?projectlore=episodes
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