Computer Talk: what does "flashed" mean?

Looking into the Verizon hotpot, MIFI 2200. On a pay as you go basis. I see this vid, and several other comments, which talk about it being 'flashed' to prepaid, and I do not know what the heck that means.

http://www.youtube.com/watch?v=dX79A4qyZFY

Here at my home, I have Verizon FIOS, wifi, all works, no issues.

Now my Dad is in nh, I am back and forth to his house (1.5 hour drive one way) for a few days at a time, clearing out, getting some repairs done. I want to be able to post items for sale on craigslist, with photos. So I need internet access. Going up to the local Starbucks and buying a coffee is yummy, but gets old, doing that to get their password of the day, and having to sit there to use the internet. Several people told me a hotspot pay as you go is going to be the best route for what I need. I was told Verizon has it, so I googled it. Can buy the unit, then for $10/ month I should have enough data space for what I need to do.

But, I thought the folks told me this is what the hotspot is made for, so I don't know what this business of being flashed means.

Thanks for some education!

Try here: http://en.wikipedia.org/wiki/Hotspot_%28Wi-Fi%29

Maybe the places that have wireless or a hotspot could tell you?