I follow Final Boss, the World of Warcraft endgame raiding podcast based out of Twitch. The creator and host, Bay, has access to the Alpha client for the Legion expansion. He does extensive reviews of each of the revised classes and specializations available live on his stream, and then edits these reviews together for a long-form video at the Final Boss YouTube channel.
Well, he got to my main character's class (Warrior) and main specialization (Fury), which has had a severe overhaul (again) for Legion. I'm watching this as I write this post, but having seen others I know what to tell you for expectation: a lot of game talk, a lot of beating upon the test dummies, and a lot of commentary on the state of the class and spec as of the client build where he did the test.
If you're into World of Warcraft, and you have a tolerance for this deep level of theory-crafting and math-working, go for the video for the class and spec you're interested in. If you want videos on the actual play, or other lore-specific parts, you want another video series; this ain't it- try Nobbel the Nobel, Fatboss, LineOfSight Gaming, Belluar Gaming, or HeelvsBabyface instead.