[Anna Hunter]

Hi!
Yes synchronization of the video and audio is not always perfectly, especially if you shoot at a distance and have very poor reference sound. I do sync for about 5 years 🙂 and always facing with this problem. Of course if you buy transmitters and all these staff, there will not be any problems. As for doing it perfectly at x, I would recommend to make it manually, do not now if it is obvious for you or not 🙂
But recently I came across one video where video transferring in real time between two smartphones and everything sync automatically, so no need to spent time on syncing, it called Microphone Rocks 🙂 Check here: https://www.microphone.rocks

Good luck!
Anna