This was a late 80s early 90s film. A nerdy type guy lets a woman and her boyfriend stay at his house. They treat him like crap, so to exact his revenge he drugs him - or both (I can't remember) and puts him/them in a wooden casket under his house. The casket has a camera and a communication system which the owner would turn on at regular intervals to monitor his progress at starving him/them to death.

At one point I remember the owner asking him, rhetorically, if he/they knew how long a person can survive without food and water.
If I'm not mistaken, he/they (spoiler alert) eventually die.

I can say for sure the film was NOT buried alive. I thought that the main male characters were Billy Zane (the baddy) and Giovanni Ribisi (as the nerdy home owner), but I checked IMDB and couldn't find anything.

Best 'buried alive' themed movie I can remember.