Sorry SE, but endgame won't work if you don't fix something.

[Orsnoire]

Ok, I hate to be that guy, because I have personally experienced the lag myself. But all of the videos linked in the OP actually show the players NOT leaving the AOE before the cast bar goes off (or in the first link, doesn't show the enemy cast bar). The video examples provided aren't helping the case.

The disconnect between animation and the enemy cast bar is huge (1-2 secs sometimes) and this is something that should be addressed, but it's a separate thing.
The current game mechanic is leave AOE before enemy cast bar finishes, and that wasn't shown in the links provided.

At this point in time, while it's not natural to avoid the mechanic that you can't visually see the enemy doing yet, you can indeed avoid the mechanic based on the enemy cast bar. Of course you're still going to get some latency issues, so don't expect to leave the AOE within a pixel of the cast bar completing and escape either.

Yeah, and how are healers supposed to watch a cast bar that isn't visible and move based on that invisible cast bar, hmmm?

They need it to be responsive so that the only way to complete content doesn't involve clunky workarounds (i.e. healers staying targetted on the main boss).

[kayuwoody]

Yeah, and how are healers supposed to watch a cast bar that isn't visible and move based on that invisible cast bar, hmmm?

They need it to be responsive so that the only way to complete content doesn't involve clunky workarounds (i.e. healers staying targetted on the main boss).

You're preaching to the choir. I've been trying to pug this as WHM for a few days now. I've found it easiest to keep Titan targetted at all times, and to heal the tank as my Focus target, and rest of party via the party frames. Essentially all my spells go in order of <mo> <f> <tt>. Knowing the rotation is essential of course, but I still get hit by stuff when I tunnel vision into healing people. Fight's relatively easy if everyone's playing their roles. The upside to all that practice pugging, I think I'm finally at a comfortable place for this fight as healer, where I will only get hit by something if I'm playing badly.