When I started using LastPass I did not have a problem logging into HULU using FireFox. Then out of the blue LastPass stopped working for that website. Just as suddenly as it stopped, it started up again, only now it goes through the logging in process every time I navigate to another page within HULU.
I discovered a LastPass feature recently which may be of help. When you go to the HULU website, click LastPass' drop down box on your right of LastPass using the down arrow (do not open LastPass). The last entry on the drop down's list should be HULU.com (or whatever website you are on). Click the arrow next to HULU.com and there you will find AutoFill, Copy Username, Copy Password, etc. Try the AutoFill first and if it does not work, then click Copy Username and click paste in HULU's username field. Do the same for password.
Sometimes when you click Copy Password (and/or Copy Username) a second list will open. If this happens for either or both entries, click Copy... in the second list instead and click paste into the HULU fields.
Unfortunately, I must do this every time I go to a Cnet.com website.