Comment on HexEdit

GAH! No matter what I do, this always turns up as a blank file (mac users should know this one, it says it can't find an application to open it)! I'd like to use this program to fool around with my Halo 1 demo, and I have everything I need except for a Edit. I run an OSX mac, and it's been able to download a good deal of things. What should I do?
PS: my email is [email protected]