Many school subjects are plurals, like physics, economics, and forensics. More to the point: mathematics. So, while it’s gratuitous pluralization, it’s not completely out of left field. To Americans, hearing a Commonwealthian says “maths” sounds cute. The other way around, I think it sounds more directly incorrect, like somebody saying they studying “particle physic” or “home economic”.
At least for the American accent, “maths” is not just a needless plural, but a homonym with “mass”. So if it caught on, it could be included on this game show.
Jeremy’s winner: math (close one, but not enough of an edge to justify the extra phoneme)
“Math” just sounds grating to me, so I’d still vote for “maths” even if it weren’t obviously correct for reasons of consistency.
You should’ve linked to the longer video with the foreign-language versions of Homonyms, though.
Beckie’s winner: maths