Hello! I'm sorry you're experiencing these problems. Are these problems happening when the plugin is running alongside other plugins or is this inside an empty project? It's possible this is a conflict with another plugin as I've never seen these problems before. If we could narrow down the possibilities of where this issue is coming from that would be a huge step toward fixing the issue.
The sound should work on pre-title movies and there is no way to disable it without going into the code so this is likely some kind of conflict causing the issue. As far as the black flash goes this is something i've also never seen happen before.
If we could locate where this possible conflict is occurring I'll see if I can find a solution.
Thank you and good luck!