It seems that the beta 18.104.22.1680 release of Maxthon prevents ads from loading on Hulu, regardless of whether ABP is disabled. It also blocks the 60 second warnings that ask users to disable ad blocking software, which means that the video stops playing altogether. When I relaunch Maxthon, Hulu behaves correctly for a short while, but soon it completely stops playing videos again. So now I'm using Firefox only for watching Hulu.
Also, can we expect to be able to disable ad-block for specific websites in the stable release?
Edit: Just discovered it's already possible.
Edit*2: If anyone else comes here with this problem, it was being caused (for me) by Adguard. I uninstalled it and everything works fine now.