Introducing SplitsBet, the Livesplit plugin that makes the viewers play with you
Ok, it was indeed linked to the negative offset. I fixed it the hard way : the bets won't start until the timer becomes positive :P
SplitsBet got (finally) updated : https://github.com/Gyoo/LiveSplit.SplitsBet/releases/tag/v0.5
There is still one thing that I could not do (see known bugs) but overall it should be stable despite all the new features. Feedback and help to fix greatly appreciated.