Freenet might be an option. There's a built-in option for versioning so changes or additions/extension to the original upload can be searched while still remaining in control of the original uploader. As for being immutable just program a client to query the content on a regular basis and it should stay cached.

On Mon, May 21, 2018 at 6:36 PM, Zenaan Harkness <zen@freedbms.net> wrote:

On Mon, May 21, 2018 at 09:28:44PM -0400, Karl wrote:
> Hi cpunks,
>
> I'm trying to figure out how to produce lengthy recordings that cannot be
> reasonably removed or altered even by a very powerful entity.

Your sole option is distribution of the recording (presumably in real
time) to multiple jurisdictions, at least one of which will be
supportive of "not deleting/ suppressing" your recording.

I imagine Wikileaks would like to know if you come up with something
better than the Tor NSA CIA mafia.