I think I found my problem. The Squeezebox is not dealing with broadcast packets, apparently at all, not even forwarding them to the TiVo. Since the TiVo apparently finds the TiVo Desktop server by receiving network broadcast packets, it's not working properly. But with pyTivo, I can tell it to send those packets straight to the TiVo instead of to a broadcast address. So far, it's worked perfectly, other than these weird second-long skips in the videos I'm playing, something like one every half hour. That might be an ffmpeg problem. But otherwise, it's transcoding PAL-resolution video to TiVo-resolution video without a problem. I should try HD content just for yuks.