As we all know most people when downloading a demo find out that they can't watch it due to obscure files that are needed for unknown reasons.

It is obvious that Quake 4 was poorly programmed in terms of demo recording, not taking into account the thousands of people around the world that may want to watch a game between two random players for Japan or even Poland.

Quake 4 netdemos insist that the person watching the demo has all the same files as the server that recorded the demo. It seems while most people know this many still have problems. So how can you get a demo to work that at first won't. Well try these tips and see how you go...

Missing pk4's
First download the essential Q4 demo playing utility Q4 Replay (Get the stable version (0.4) as the new version has problems playing demos from non-q4 directories). This we be able to tell you if you have all the files that were on the server.

Note: Older versions of maps will cause problems. Removing old versions of maps from your q4base directory even ones that are being played in the demo. It can also help sometimes to remove non-referenced pk4's (ones that are not in the q4replay list). There has also been issues with the VIA Map Packs downloading the maps individually seems to solve this problem.
demo_enforceFS "1" can also be helpful in this situation, but has problems of its own.

gamex86.dll Problems
Second problem that people have is mismatched gamex86.dll's. This problem is generally caused by different version dll's being in your Q4Max directory. A note on installing Q4Max - DO NOT leave old versions in the directory. When installing Q4Max delete or move your old directory and create a new one using only the new files. This should prevent gamex86.dll problems. Also make sure your gamex86.dll is NOT writeprotected.

Error usually looks like this.. Failed to spawn entity with classname 'XXX' of type 'idPlayer'

Playing Old Demos
If you want to play old demos from previous versions of Q4Max, you can do what I do. Have several Q4max directories, I name them q4max70 (for Winter CPL demos) and q4max71. TRo use these older versions when playing demos again Q4replay comes in hady, usw custom mod and type in the directory name. This will also work for x-battle, but is less of an issue as there is more backward compatibility. i.e. 10-12 and 4-5.

Black demos / No lights
This is due to some 'performance' tweaks, if you create a server of the same map and then play the demo, if should work fine. Setting defaults in Q4 also solves this problem and using Q4Max GUI to alter things.

Democasts
Because democasts use pk4 files that are not originally referenced in the netdemo demo_enforceFS must be set to 0 or no commentary will play.

Just trying to get some solutions in a collection if anyone has more problems or different ideas please comment...