I notice when I try to download the file, it shows immediately that the exe file is dangerous. Should I be concerned? 
no, it is self signed. So most small programs made will be self signed and "dangerous". This is just microslop being microslop and asking people to pay for certificates to make their applicatoin legit for a windows system. Has been going on for a while. There are ways around it, but not really worth the hastle for such a little application.
Hope this explanation helps.
ps: love the reaction image