It's not realistic to expect that everyone has strategies memorized and you always need to go over some of the key things before first attempts. Let's be honest, there's a lot of different spells going on in each fight and explaining them all in detail leads into a huge wall-of-text that no one likes to read, plus majority of those abilities don't concern all the players anyways.
Another thing I want to touch on is your forums. Forums are supposed to be an extension of your community and if your players are not using it to interact with each other, they are probably not going to visit it just to read boss guide that's been copy/pasted from somewhere else. Instead of maintaining a strategy catalog, why not try interactive think-tank approach where you go over couple things you didn't have time to figure out during the raid and talk amongst each other on how to fix them? Although this can be hard if you don't have enough people in guild to keep forums alive.