update all "video" declarations to say "ytid"

I pulled down your repo during a hackathon and realized after scouring the library that "video" isn't actually defined inside the component, and that the ID is actually called "ytid".

I almost showed off how quickly you can get something up and running with ember-cli and a couple of plugins ;)

Once I got it working I discovered this is a very nice wrapped on youtube. Thank you!
Merge pull request #4 from jkatsnelson/patch-1

Update all "video" declarations to say "ytid"