What is the ruling on speaking against one's father out of a need to vent one's fear of him, and what is the ruling on hiding the television from him in this situation?

You should thank Allah for the blessing of adhering to His obedience. Your father has a great right over you, as he was the cause of your upbringing in goodness. It is not permissible to speak ill of a Muslim in their absence, and this is even more emphasized concerning one's father. It is permissible to speak ill of one's father for a valid purpose, such as reducing awe of him, to the extent that achieves the intended goal. As for your father preventing television, obedience to him is not obligatory unless the prohibition is for a legitimate reason, such as indulgence in forbidden things.