I've created a ticket to make sure this glitched state (free-cam on live server) will not be possible in future versions. I would strongly recommend against doing it on purpose as it may be considered cheating by Watchdog and will probably result in a ban.
Now, let's deal with the second bug, the one that prevents the replay from properly loading in the first place. Please post the contents of the fml-client-latest.log
file inside the log
folder inside your .minecraft
folder to some pastebin site and link to the post here.
Note that this log will only contain information on the last time you started Minecraft, not any previous runs. Again, make sure you only try to open the replay, do not join any multiplayer servers while in that bugged state.
Could you upload it to some file sharing site?
If you don't know which site to use: https://filetea.me/ doesn't require any signup, has no nasty ads and no limits on file size. You do need to keep the page open in the background though until the other user has downloaded your file because it is never stored on the server.