As far as Seafood buffets, there's Todai, which is a Japanese seafood buffet, so one side has sushi, chilled cooked crab legs and other cold items, and the other is hot food, including lots of hot seafood (including lobster at dinner), all you can eat. The closest locations I can find to Anaheim are
1500 E Village Way # 2203, Orange, CA
Todai Restaurant Westminster
2008A Westminster Mall, Westminster, CA
Both look to be about five miles away.
There's also the Asia Buffet in the Buena Park Mall, on LaPalma between Beach and Magnolia.
8360 La Palma Ave, Buena Park, CA
It's sort of Pan-Asian: Chinese, Japanese, Vietnamese, etc., including sushi and hot seafood dishes.