How do you remember mechanics?

[CupDeNoodles]

I would first ask what videos you're watching. A youtuber by the name of MTQcapture makes great dungeon and raid guides. I watch her channel for learning mechanics.

https://www.youtube.com/user/MTQcapture

As for remembering, I play this game baked and even after watching her videos I still forget. It's honestly the constant spamming of dailies that I eventually do it by muscle memory. Plus you have tons of repeating mechanics too. The whole stacking symbol let's you know it's time to run for your teammates so remembering what they look like helps too.