you can do it much easier

Open Notpad

Start with @echo off. Then start each line with Start, space, then add the full link to the site. when done save it as a .bat file. It should look like this.

@echo off

Start https://www.youtube.com/

Start https://www.twitch.tv/

Adding other browsers is simple also. Name the browser before the link

@echo off

Start Chrome https://www.youtube.com/

Start Firefox https://www.twitch.tv/