WatchOS 1 doesn't really support video, although you can do some tricks with snapshots or animated gif.
That demo in the first watch release presentation was a security company, showing a garage camera, if I recall. That was a mockup, and not actually possible quite the way it was presented at the watch announcement. (More of a 'one day in the future we'd like to do this' presentation, by the Alarm.com/ADT guys, I think.)
Watch display looks good. The update rate can be set for anywhere from 1 second to 60 seconds. But my device only sends updates every three seconds so to see any movement takes 3 second intervals. Might be better with different cameras. Here's a screen shot of mine.Looks slick. How does the watch display look? What kind of update rate is it giving you for display? Looks like a good setup, although a little pricey at $9.99 US.
I'm using this app on my watch to view cameras with very good results.
ekeypad video
eKeypad Video by eKeypad Mobile Solutions LLC
https://appsto.re/us/a1WZt.i