There are two approaches, and you might combine them.
Wowza's nDVR features will work. nDVR has a WindowDuration setting that will be important, how much of the recording is preserved. Then to enforce the 6 hour delay you can use the
Playlist Request API
The other approach is using Wowza
Live Stream Record and its segmentation features, and
this scheduler,which can use files as the source for a live stream rather like a re-run in that everyone sees the stream as live, though it is a file source. You might record in 1 or 2 hour segments, that will feed this schedule. You might work out some naming convention such that the schedule can remain static, but the files it uses are changing because of your re-naming scheme. To facilitate the naming scheme, take a look at
I think the 2nd approach makes more sense for a 6 hour delay. It should be more manageable, precise and the recordings are portable whereas the nDVR recordings are chunked and not useful for other purposes.