Why wont most digital SLR cameras shoot video?

One of the best features of most new digital cameras is their ability to shoot little video clips. I've been looking into getting a nice digital SLR but cant' find one with this feature. Why not?

its a 'slr' camera, firstly it has a single lens riflex mechanisim and second it is used by pro-s. they donot shoot video at all. some semi dslr cameras shoot videos like the Sony h2, lumix fz30 and many more.

because SLR see the object using a mirror, they don"t have Electronic View Finder. And you only get mediocre video using digicam, cannot compete even with the cheapest real videocam

Above answers give the real reason, but by the time you are ready to pay for a DSRL, you are pretty much not interested in playing with video. The quality of video isn't that great anyhow.

An dSLR uses a completely different (and superior) system to that of a fixed lens digital camera. It's not a system that can easily be modified for video.

Anyhoo, if you want to shoot video, a Sony Handycam will give you much higher quality video than a digital camera and is cheap as hell.

Well, if you want to take real video.. get a video camera. Just little clips you want, you're going to have to go with a regular Dig. Cam instead of the SLRs.. Why do the SLRs spark your fancy anyway? Are you just going to be taking regular pics and you just want a nice zoom and pic? Theres quite a few high optical zoom cams with high megapixel if you want to enlarge the pics also. Try Sony.