The switchblade_v31.zip file you have requested: Utilities / SwitchBlade - 1000kb is not available. Perhaps try browsing all files for the game Doom III and upload any files you want to share or are missing. This is the only information we could locate:
The Switchblade Video Encoder has been updated to 3.1. It is nearly 3 times as fast as 3.0 and quality has improved too. It also now includes a front-end written in Visual Basic so it's noticeably easier to use, and an MPEG-1 video converter for Linux users.
NB: The author has developed the front-end using (supposedly) a beta version of Visual Basic 2005. Hence, you will need to install Microsoft .NET Framework 2 Beta 1 before you can use it.