Are there any yet? Would be cool to get a sticky up regarding the basics of the upcoming fights so guilds like mine who do not have enough people interested in doing the PTR raid testing are still able to hit the ground running!
Icy Veins indeed does have previews for every single boss, I watched all of them so far myself, about as close as you are going to get to a guide atm. Method has quite a few videos up as well with vent commentary.
Scroll down a bit and check out some of the playlists, they are seperated into guides for each role. They dont seem to be complete on number of bosses but there is a good few of the bosses there already
You can also start forming strats yourself. For example, I'm going through the dungeon journal and retyping all of the abilities in an "easy-to-read" format for my guild. Instead of saying some random craziness with word fluff, I type "deals 200k damage to all players (interruptable)." While this does not incorporate the timing of these abilities, you can at least read through these abilities, understand WHAT they do, and then watch a non-strategy video and observe how the mechanics are played out. Then, use your brain to synthesize "this ability SAID it would do X, and I'm watching something similar on screen, so that must be how this works."
It's not for people who are not motivated by this kind of thing, but it doesn't take a lot of time.
Just wait, in my experience most guides get published the day the patch hits because certain abilities of bosses may be changed if necessary.
Posting info before live can really damage the player base, a example is that certain warlocks still wonder if they have to use fel flame in their rotation because at some point a single person wrote it because according to hits ''test'' it was a dps increase (not sure if he even claimed that it was a dps increase).