Strange... JRiver Video Codec isn't an option. I also note that when recording using the default JRiver Codec, AVICodec tells me the video is "Video : 1 Mb, 2420 Kbps, 31.750 fps, res. 320*240 (4:3), DX50 = OpenDivx V5, supported". Yet, I don't see OpenDivx V5 as an installed codec with in Device Manager.
You are having the same problem that a few other users have experienced. For some reason the JRiver video encoder and decoder are not properly registered during installation. When the program can not find JRiver Video codec, it tries to find a few other codecs, including Divx.
To fix it, run the following commands:
regsvr32 C:\Program Files\J River\Media Center\TV\MJVideoEncoder.ax
and
regsvr32 C:\Program Files\J River\Media Center\TV\MJVideoDecoder.ax
Yet, I don't see OpenDivx V5 as an installed codec with in Device Manager.
The name appearing in Device Manager may be different from the name my program retrieves. At least you do have DivX on your machine, but may be just named differently. Also some DirectShow codec filters do not appear in Device Manager. On my machine, DivX shows up under "Video Codecs" in Device Manager as "DivX 5.0 Codec", but it is known as "DivX 5.0.2 Codec" in MC - not a big difference here, but at least some.