This looks pretty interesting.
A small thing: For cancelled DELETE requests like shown in the video, it would be better to return 403 Forbidden [1] instead of 400 Bad Request [2]:
10.4.1 400 Bad Request
The request could not be understood by the server due to malformed syntax.
Vs. 10.4.4 403 Forbidden
The server understood the request, but is refusing to fulfill it.
[1] http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html#sec10...[2] http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html#sec10...