Somebody else will have to deal with this one, Rita.
It doesn't look at all difficult, but I dunno how it fits with what's been posted.
I just checked with OWC, and a 240 GB replacement SSD for the MBP you're looking at costs $269 + tools, which seems like more than it would cost from Apple. (Maybe somebody should double-check me.)
More: I just looked at
Customize MacBook Pro, and an Apple installed upgrade from 128 GB to 256 GB for the newest low-end MBP costs only $200.
Still more: You could sell your 128 GB SSD, but that could leave you in a bad position as respects your AppleCare.
And even more: What strikes me as strange is that the SSD housing in the video looks like it was designed to be user serviceable despite the fact that Apple says that it isn't.
