[MEDIA_PIPELINE_TF] Merging use cases 42 and 43

I have created a new use case (http://www.w3.org/2011/webtv/wiki/MPTF/MPTF_Discussions/Delivery_to_ip) that merges the current use cases 42 and 43. I've broadened the language to reflect the discussion on today's MPTF call. If we agree on this use case then we can drop 42 and 43.

Regards,
Bob