It won’t mess up anything, since going to Hulu (or anywhere else) from inside your network will only be affected by outbound rules. It would only affect you inbound if Hulu was doing a push to your network on some port that you are port forwarding, and afaik Hulu doesn’t do that (it would be a demand push, and you wouldn’t want that in any case).
My suggestion is just try it and see for yourself. It’s really the easiest way to learn. If you totally mess it up, then reset the router to default and then reset the rules until it works like it was working before you tried your experiment. It helps if you have a router that lets you save your config, but if you are like most people you really just have your router set up mostly (or fully) as the defaults out of the box.
-XT