I can see how some people might think its "cargo", especially the first time she says it. the T sound is light when she first says it. and a long 'A' can sound like an R. and i guess the 'c' just came from your mind wanting it to be there :-p
anyway, the 2nd time she sings it. the "T" is very clear and louder.
like I said earlier, you're probally expecting to hear her say "to" pronounced properly, with an 'O' sound"
and since you don't hear that, you expect it to be a different word.
but, like I said, sometimes people say 'to', and make it sound like "ta" this is very common in my area, where Vanessa grew up :-p
so in conclusion, i still think its 'to go across the sea'.
