Why can't I..?

When I try to watch this video I get that error ^ I'm guessing I need to uninstall half-life2, which I have (Well I think I have I went to control panel and then add or remove programs and it isn't in there anymore) Because everyone else can watch it, and I want too to.
Here is the link to the video:http://s20.yousendit.com/d.aspx?id=3...M2JB6M8Q4HDPGW

Edit: Sorry it has all that white.

You need to place it in your /cstrike/ directory, and open it via the HL2/CS:S console.

I didn't record it on CS:S or HL2. I recorded it on CS 1.6

Well, open it in CS 1.6.

After you install HL2, .dem's become associated with HL2. So just open it in the console of CS 1.6

How come other people that play cs don't get that message?

Perhaps they have only 1.6 installed, and not HL2.

I uninstalled HL2.