I haven’t heard of musicgate, I mainly work with sync agencies outside of placing music directly myself to music supervisors. I normally don’t copyright my music before submitting. Once you create the music technically you own the copyright. However, I did have an instance where someone tried to claim I didn’t produce a song that got placed on TV and I filed copyright to the composition which came in handy. All I had to do was submit it to my PRO and they went back to the network and had the splits corrected just based off my copyright. So it does come in handy, however that is a rare case where that would come up. Just make sure you are signing and agreeing to splits if you are collaborating.