I want to be able to watch my demo's. I tried VLC but it doesn't work. I just want to watch for kicks.

Also, is there anyway to convert a .dem to something I can upload on youtube? Thanks.

As far as I'm aware UT is the only application that can replay recorded demo files - if you're using Demo Manager, you can use the PLAY button to rewatch a recording. Otherwise use the 'demoplay' command in the console.
If the file is called 'mydem.dem', you'd use

demoplay mydem

...er, actually, I'm not sure whether you need to specify the extension.

To generate a video file you'd need to use a separate tool, Fraps is the most obvious choice, but it's a paid-for solution. I've never used it, or any of the alternatives, but there are a few other applications that purport to perform the same functions.

I know how to watch a dem on UT, I just want a tool so lets say I can click on a .dem file and boom, I can watch it.

I already have that. That's how i make the DEM, but I don't just want to view it in UT.

You should use Fraps and re-record the demo. It will create a file with a playable format. Youtube doesn't support many formats, so you'll need to use a converter, to convert the file to .FLV format: http://www.erightsoft.biz/GetFile.php?SUPERsetup.exe
Then, upload it to Youtube and post some links.

Link for Fraps?

http://torrents.thepiratebay.org/5439499/Fraps_v3.1.0_Full_Registered_Version.5439499.TPB.torrent

What happens when you double-click a .dem file in Explorer? The file association exists for my install, so UT launches and goes straight into it. Or I imagine it would if it didn't crash during startup - there was a UT-demo playback bug that required an update, but it might be because some of the required files that were present on the server where/when the demo was recorded aren't available...

uh, well I try to open .dem through many applications, unaccepable.

So does anyone know what I can convert .dem to in order to put it on UT? I got a sick ass game I played with soge to put up

For Youtube use either .FLV or .WMV.

so convert .dem to flv or wma?

Direct conversion isn't supported, so you need to use Fraps.

In other words, you run Fraps at the same time as UT, and it records what is being shown on screen.
Again, what happens when you double-click a .dem file in Explorer?

It asks me which program u want me to open with.

And yeah, I tried recording with fraps and there's no sound. Still trying to figure it out.