Alrighty, since Elly is getting ahead of things, I figured I ought to as well
I'll initially just have links to Elly's separate posts and will add links to external sites as they come up. As always, feel free to post your links to guides and videos and I'll update this post at least once a day when there's stuff to update.
Remember we'll also have the Dungeon Journal ingame too, so we can get some idea of what each boss does there as well as these guides/videos (in other words, don't go "I don't need guides it's all ingame!" because, I assure you, it isn't).
Some general info - the instance has seven bosses. The first four bosses (Beth'tilac, Alysrazor, Shannox and Lord Rhyolith) can be done in any order, but all must be downed before proceeding to the final three (Baleroc, Majordomo Staghelm and Ragnaros).
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The Firelands
Complete listing of all seven bosses directly from the ingame Dungeon Journal - Wowhead News.
Single page with ALL boss encounters on, using Tankspot videos: Wowhead News. Includes Occu'thar in Baradin Hold.
Shannox
Ellyspot - Elly's paraphrased tactics from 25man.com
Tankspot - video and tactics
Video - LearnToRaid.com (NOTE: on live servers, the dogs cannot be taunted)
Beth'tilac
Ellyspot - Elly's paraphrased tactics from 25man.com
Tankspot - video and tactics
http://www.youtube.com/watch?v=L8OQFgKTn_Q - LearnToRaid.com
Alysrazor
Ellyspot - Elly's paraphrased tactics from 25man.com
Trash video - Boss Fight Video
http://www.youtube.com/watch?v=GTD2ciqd3CM - LearnToRaid.com (10-man)
Lord Rhyolith
Ellyspot - Elly's paraphrased tactics from 25man.com
Tankspot - tactics and video
Video - trash gauntlet and boss video.
Video - LearnToRaid.com
Tank PoV - tactics video.
Warlock PoV - Kill video.
Baleroc
Ellyspot - Elly's paraphrased tactics from 25man.com
Tankspot - video and tactics
Majordomo Staghelm
Ellyspot - Elly's paraphrased tactics from 25man.com
Tankspot - video and tactics
Ragnaros
25man.com - tactics
Tankspot - video and tactics
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Cog