When you say connect, do you mean simply tap both connections to the battery? How would you "connect?"
If you already have a jump starter, why would you want a 9v battery? Is it safer/gentler? The video is pretty simple with a jump starter. Thanks for sharing!
Others have already answered, but I'll reiterate.... simply tap both connections to the battery.
I don't carry a jump starter anywhere, but I can find a 9V battery at pretty much any convenience store, and in a pinch I could probably find other 9v sources as well.
It may indeed be safer to do with a 9V battery, other than it being less clear which connection is positive. A 9V battery will only supply a few amps to the circuit if you put it backwards, and at least some electronics will not meltdown in that case. That jump pack will supply a few hundred amps for a short period, and that'll literally burn whatever it touches that's not built for it. I suspect there are protections in that connection cable against reverse polarity anyway.