I got the same problem too. I click the “record” button, and I choose that Largarith codec. After that I’m clicking configure, and swapping RGB with RGBA. There are also some boxes in this window, but I leave them unchecked. I click OK, and OK again. Then a Windows with lots of different functions appears. Around the middle of the box there is a function called “Save Alha”, and when I click that one more boxes appears. Are they supposed to be unchecked? Or? I’ve left them unchecked. When I’ve finished rendering I export the AVI file to Vegas 9. I drag them into the timeline, and right click on it choosing properties, Media and swapping “Alpha channel” from “none” to “Premultiplied”. The background color is black. I click OK. Now, I’m importing a windows movie. Wildlife or something is it called. I drag it below the PI movie I made, and click Play. The only thing that I can see is the wildlife movie playing. I can’t see the “effect” that I rendered with PI and imported into Vegas.
Can you possible help me :)?