@Helen0609 If you are just filming yourself playing (and possibly singing) and then want to go back and put another audio track on such as a vocal or harmony vocal - that is relatively easy with some software because you can record that on to another track in the software. You don’t need to record that separately and synch it. So you can just really concentrate on the guitar playing which is really what we all want.
Where it gets slightly more complicated is if you want to add a second video track - then you need to synch the sound. If you look at my last AVOYP of “All Your Love”, I did the rhythm guitar and vocal as one take like as a backing track. I then went and did another video of the lead guitar part to add that and had trouble synching the audio with this because the second video had the lead guitar overdubbed and the audio was not identical. But I got there. NB: you need to scroll to the end of the thread to see the edited takes: