I do agree that the kids may learn. ... not about general relativity in particular, but about doing experiments and the notion that ideas can be "tested" to see if they are really true or false.
Give kids a little bit more credit than that...
The boys look like they're in 5th grade or so...the girl looks like she is probably in 3rd? They aren't infants, and their dad obviously works in this field. This was a great opportunity for them to see what dad does beyond sitting in a lab all day.
When I was that age I would have been ecstatic to see what my dad did, doubly so if it had had something to do with science.
Knowing that a plane flies vs. knowing how it flies is a valuable thing indeed.
Kudos to this dad for encouraging curiosity in his children. All too often this trait is squelched.
I can say that has been the case for me personally. I was shown lots of cool stuff when I was a kid, I didn't completely understand it then, but I have been able to look back on past experiences to help me make sense of concepts I ran across again later.