Welp, looks like Mochi’s Version Control is offline (Mochi was shut down recently). World 3 used it reduce the size of the actual swf file that was distributed on sites, so the game just isn’t playable without that chunk of game being piped in,
I’ll have to revisit that mammoth fla and create a full version eventually, but at the moment I’m way too busy trying to finish up the World 1 Remix, so for your World 3 fix, you’ll have to go to a site that’s hosting the full version. Two that I know definitely have the builds that still work:
Games.com has a newer version that streams the levels in as they’re needed, levels take slightly longer to start, but there’s way less upfront load time.