I usually use firefox with the latest plugins, but I just tested it with IE8.
On IE8 it is taking a very long time to buffer and I have a fairly fast connection (5Mbit).
If you are using anything other then flv for your trailers like quicktime (quicktime is good for
editing but not good for the net) or realmedia (realmedia has a good file size for
sending acoss the net, but not for streaming) you should convert to flv for videos,
if for no other reason then it buffers fast and plays quick.
The Riva converter used to be free but now they want money (sic mundo transit)
there are still some copies of the free version floating around on the net. If you like
I could email you one.