Currently, running the run-safari command on locally built version of WebKit, or using my modified version of the WebKit launcher, hulu.com hangs just after its initial load, indefinitely. However, the official nightly doesn't exhibit this behavior. I believe this is due to the nightly including a newer version of the WebKitPluginHost executable than the one the locally built version uses (which is just a symlink to the version included with the system WebKit framework). Copying the newer executable from the nightly to the locally built WebKit.framework directory fixes the issue and allows Hulu and other Flash sites to work correctly. Seems like a simple fix, if that version of PluginHost is available for the repository.
*** Bug 49146 has been marked as a duplicate of this bug. ***