If you have Windows 10 the simplest way to record it is to just hit Win btn + G while you have BSim running.
Otherwise OBS (
https://obsproject.com/) looks like a good freeware product.
Geoff, what do you use?
Yep, that's what I do. In the past I've tried a number of other techniques but the software was always flakey and the files were generally huge. I used to restort to pointing a iphone at the screen, but the WIndows 10 Game Recorder is much neater and easier.
I do have to try and track the action, which can be difficult as the Bkool sim doesn't make it easy to track 20+ riders and see where riders are close together. I've found using a second Bkool sim logged in using my wife's bkool account allows me to flip between riders to find battles, then I can switch the recording to those riders.
It would be nice if the spectator mode had a "follow the action" mode, but I don't suppose it is a priority to improve the spectating!
Geoff