I looked into using ffmpeg to “compress” video podcasts by lowering the framerate a lot, but it didn’t seem to do as much as I thought (about 50% size reduction). The theory was that a video podcast is mostly talking heads with an occasional chart on the screen, so you really only need a frame every second, or five seconds.
Reducing framerate doesn't help much when there isn't a lot changing between frames. Here are some better optimizations:
Noise reduction, so you compress less useless noise: -vf hqdn3d
Turn up the Constant Rate Factor. This will make better visual tradeoffs than decreasing frame rate. 23 is a good starting point for h264, but keep increasing it until you don't like how the content looks: -crf 23
