Of course, people don't use language in a consistent way, and people will use terms thinking they mean e.g. their antonym.
It's probably a common initial reaction to learning of impending parenthood. Life will never be the same. Initially one might only see the looming challenge of the mountain to climb.
That kid will be 10 soon.
I suppose the woman filming the video could have taken much longer to realize (unlikely, but possible), or chose to wait to tell the father until several months later (also unlikely, but possible), but either way, the kid is turning 10 now-ish, not 11.
It's also possible that this video was posted well after it was taken, in which case we can't say much about the age of the kid, except that it likely happened before this "Share to YouTube" functionality was removed from iOS.
(By the way, presumably there are still about 9 months to go in that pregnancy before the child is born.)
A couple hours after posting this on my site, I found this incredible vid of a woman telling her partner she’s pregnant. Incredibly heartfelt, and only 16 views https://youtu.be/refKFdcojlE?si=l-PssLVYmmOPjjjA
It was posted over 10 years ago. I wonder if the family even knows that this video still exists.