My latest Ultraviolent Ao100 demos require over 3MB - Perhaps 4MB would be safe. I'm taking sporadic runs at N! Ao100 - that might take even more space, should I eventually succeed.
willhostforfood isn't a bad host, it has no captchas, delays, etc to download, and doesn't even require javascript.
Still, I do see the advantage of storing the file with the post on the forum.