From Populous Wiki
With fraps, the resulting file format is uncompressed avi, which would need to be compressed using a separate piece of software such as VirtualDub or Any Video Converter. This will dramatically reduce the file size (over 100 times smaller), resulting in a file which is ideal for uploading to a web server. For further editing effects, windows movie maker or a similar piece of software can then be used.
However, recording full games would require a lot of space. In this case, using screenshots or small clips to make a video would be more appropriate.
If you are the host make sure your not slowing the game down causing the other players to lag.
More recently there are tons of programs to record populous with, or even streaming. OBS (Open Broadcaster Software) works for both cases.
A very useful set of tricks and glitches made by user Dakini Shaman by recodring content from Populous: The beginning The Dakini Shaman Youtube User Page