Minor changes on how demo files are recorded and stored.
Move the recording of demos from each client to the (dedicated) server. Store them compressed and offer them to the clients.
Move the recording of demos to the (dedicated) server, store the demos compressed (e.g. bzip2) and offer the download to clients.
This feature should be added to the client, so demo files can be used to spectate every player. To offload some work from the clients and to save some HDD space.