View cache of facebook thread in firefox? (need help asap)

Hey all, I have an issue with an abusive mod banning me and another member on a facebook group, now I have screenshots of part of the thread but apparently something else happened which would also be good to have proof of.

Now I went into the “about:cache” of firefox and believe I have the right thread (in memory cache) but I get the “content not available” message meaning that it is just trying to get it through facebook.

How can I reconstruct this/view the thread using what is in the cache for it?