my dad barely beats us up, but when he does, he goes overboard?

So my little brother is 6. He's really spoiled, and barely listens. So today my dad told him to increase the volume on the TV (the remote isn't working) and he's like "no." So my dad smacked him on his foot and demanded he raise the volume. So then he raised the volume, and then ran to another room and started crying. So like 5 or 10 minutes later, my dad goes to him, drags him back to the living room, and then starts beating him up. I think my mom was on a different floor (I was sleeping this whole time) and he ran up to her and cried in her arms. My mom got mad obviously.

Don't you think that was completely unnecessary? I mean he smacked him that first time on his foot(even though I don't believe in hitting at all). But then after 5 or 10 minutes he suddenly decides to go hit him? He claims that he waited so that he could calm his anger instead of beating him while he was angry because it would've been worse. How about you calm your anger and go talk to him about what he did?? He's SIX. How much anger could he even cause you for you to beat him up?

He only hits me like probably once or twice a year, but last year he pushed me so I was crying to my mom and then she got mad at him, so then he starts beating me nonstop and attempted to drop the couch on me while I was on the floor just because I told my mom and she got mad. Well that just made it worse and they got into a days long fight.

When my mom hits sometimes, it's a few slaps. But he goes waayyy overboard.

Opinions?