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

[Silverwalk]

If you've actually watched the video with the bard closely, you can see that the player wasn't out of the weight during it's cast time. If you pause it at the right time, you can clearly see the cast time is over with the player still 3 or 4 steps inside the weight. The damage does not get applied to the player until the animation is complete, which is why it looks like lag.

I don't know which video you're referring to, but check this out:

http://www.youtube.com/watch?v=QsHuXAl-bOY
At 6:21 landslide cast begins
At 6:22 player leaves aoe with cast bar at 75%
At 6:24 player is hit by landslide and knocked off

Freeze just after the player leaves the AoE, cast bar is 75% - landslide.