kierenj:
Ok, for anyone else, the battery connector is:
2-way JST PH
I'm really stuck with this ~200ms latency receiving UDP packets, though. Multicast or not, there's a chunky initial delay "sometimes". If I send a lot, it seems to deal with them quickly ish, or in batches or something.
Please, can anyone give any guidance on this? I'm stuck! Is it the same with TCP? I could use multicast to discover devices then TCP, but I went with UDP because it's usually lower latency!
Hey, thx for updating your progress!
I just found out too, that it is a JST 2.0 PH. 
I just looked that one up too, because I want to power my MKR Wifi 1010 with batteries, which are in series like in that video to use the right amount of Voltage, while powering the board:
I'm a newb and I barely find any information about how the power inputs work. The LiPo Connector exactly needs 3,7 Volt I guess? I'm kinda thinking about using a 5 Volt downstepper (Pololu 5V Step-Up/Step-Down Voltage Regulator S7V8F5 - POL2123) for my powerbank consisting of 4 of these batteries in the second video, which are in series, to achieve around 5 Volt required for the VIN Pin to power the board.
I've found the batteries for instance here: https://www.ebay.de/itm/4x-Ni-MH-AA-Akku-1-2V-3000mAh-High-Power-fur-Solarlicht-BC917/352708061329
I want to put these batteries inside a box like that: https://www.ebay.de/itm/Batterie-Kasten-Halter-Batterien-Kasten-4X-18650-im-parallelen-3-7V-Pole-Lo-Y0B9/172794994746?hash=item283b62603a:g:xqIAAOSwn-tZJ8zG
I'm not sure, if it's the best way to do it and if I shouldnt take another route, which involves the battery connector on the board. It's so weird to me, that there isnt a screw-type terminal like on the MKR WAN 1300 (green little block on the MKR WAN 1300), where you can put the ends of your jumper cables connected to your battery into that terminal. You could easily screw these jumper cables into the screw-type terminal.
How did you solve the power bank issue, if I may ask? I'm curious. 
I'm working on a project, which involves a ultrasonic sensor, a SMS alert system and ofc the MKR WAN 1010.