ZouTube is the dedicated YouTube app for Maemo, installable from the App Manager. Or you can just use YouTube normally from the browser.
Hulu is a very Flash-intensive site, much harder system resources than YouTube. It strains the capabilities of some desktops. Not even the N900 deals with Hulu well right now. When Flash gets updated from 9.4 to 10 sometime after the first of the year, then the N900 will probably be able to handle Hulu.
