After the program has run a few times, I get "could not load certificate authority" and the programs hang.
Could you please try doing a full reinstall and see if that helps.
What you will need to do is delete the app (uninstall) from Applications instead of just reinstalling over it. Then in Finder go to the top menu and then access Go > (holding one of shift/alt/control/command) Library > Application Support > Jaksta Media Recorder and delete that folder (NOTE: doing this will erase your library file list in Jaksta, but your downloaded/converted files will remain intact). This folder and its files may already be deleted when the app is removed, but it's a good idea to double check and be thorough in case it remains and is reused when the app is reinstalled. Reboot the Mac and then do a reinstall of the latest version (https://www.jaksta.com/download/mac/jaksta-media-recorder) and it will regenerate a new copy of the deleted folder and the application files.
If there is a break in the programs processes, then doing this should reset it.
Start with that and let us know if the problem continues.