I have an issue when using Air Video where the buffer will fill up very slowly over an adequate WLAN connection going from my wired computer to my iPhone 4.
I'm not using live conversion, so I don't think my computers processing speed is an issue.
I'm using the latest non-beta Air Video server and client.
Trying to play even a 2.5 mbit/s video over the local network results in long buffer times that can't keep up, and it eventually pauses to buffer.
I've tested the internet connection on my phone at 10 mbit/s via speedtest.net app.
Switching to 802.11n to 11g seems to help the problem, but not cure it, even though I get the same speeds on either one in other apps which seems odd.