Every video I see where someone complains about the lag I can usually immediately pinpoint that it's the player's ISP. Take for example the first video referenced in this thread:

http://www.twitch.tv/sunarierymshek/c/3084552

At the very beginning of the video you can notice that this player's screen is lagging like crazy. As his party runs down the ramp, you can literally see stuttering and even a fast forward effect. If you have a good ISP you should NEVER see a fast forward effect. The fast forward effect occurs when your ISP cannot download the data fast enough causing objects / players to freeze in place for a split second when in reality they are moving and once the lag ends the game fast forwards the characters into their correct current positions. I'm sorry, but i'm watching all of these videos and the players just all seem to have awful awful ISPs.