Error in Software Sources in Ubuntu 9.10

Hello. I recently "upgraded" to Ubuntu 9.10 from 8.04 by uninstalling the latter and doing a fresh install of the former. This version rocks. It really looks good with my 22" monitor.

Now, here's the problem. I tried tinkering with software sources because I wanted to install cinelerra. It's got these on the 9.10 part of the "Get Cinelerra" page:

9.10 Karmic Koala

    for all x86 (full working on 32 and 64 bits), by Paolo Rampino:
    deb http://akirad.cinelerra.org akirad-karmic main

        Installation notes:
        - For your convenience you can install a package for detecting your version of Ubuntu, installing akirad repository and keeping it updated.
        Just double click on the link http://akirad.cinelerra.org/pool/addakirad.deb and install it with GDebi Package Installer.
        Alternatively, use one of the following terminal commands:
        wget -q http://akirad.cinelerra.org/pool/addakirad.deb && sudo dpkg -i addakirad.deb && rm addakirad.deb && sudo apt-get update
        or
        echo deb http://akirad.cinelerra.org akirad-karmic main | sudo tee /etc/apt/sources.list.d/akirad.list && wget -q http://akirad.cinelerra.org/dists/akirad.key -O- | sudo apt-key add - && sudo apt-get update
        - 7 are the packages available in the akirad repository:

            Comunity Version of Cinelerra

                cinelerracv (all computers)
                cinelerracv-gl (best on computer with opengl2.0 shader)
                cinelerracv-smp (best on multiprocessors computer, it allows also opengl2.0 shader)

            Simeon Völkel merge between CinelerraCV2.1 and CinelerraHV4

                cinelerrasv (all computers)
                cinelerrasv-gl (best on computer with opengl2.0 shader)
                cinelerrasv-smp (best on multiprocessors computer, it allows also opengl2.0 shader)

            Utility

                cinelerra-swtc (extra Shape Wipe Transitions)

        - Ubuntu Karmic uses Pulse Audio as Sound driver. Since it comes with a PulseAudio ESD compatibility layer, Cinelerra can be set to work with PulseAudio. Simply open Cinelerra and go to Settings->Preferences->Playback->Audio Driver. Select ESound and set the following parameters:
        Server:
        Port: 7007
        - These packages set shmmax to 0x7fffffff and add non-English language support for Cinelerra.
        - Please, report any package bug to akir4d at gmail dot com

I assumed that "deb http://akirad.cinelerra.org akirad-karmic main" is a repository (if that's what it's called)/software source, so I put it in the software sources of my system. Now, it said "Reload" after putting it in, but after some time, it says this:

W: GPG error: http://security.ubuntu.com karmic-security Release: The following signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu Archive Automatic Signing Key <email address hidden>

I thought all I needed to remedy the problem was to remove the address, so I did but the problem still persists.

Sorry for the intro, and long post.