Thanks Arindelle.
I am using WASAPI exclusive mode. I haven't set up a separate zones as yet because in all my testing I haven't found a setup that actually works for external video sources using the WDM. I tweak settings in the one zone and when it doesn't work, put them back. My understanding is that I only need separate zones when I want to use one zone for audio only, with decent Buffering and Latency settings to avoid artefacts, as it doesn't matter with audio only, and the second zone is for video playback where I need to minimise the Buffers and Latency settings to achieve the best lip sync I can, perhaps while suffering a little sound degradation.
Using the YouTube sync videos is a good idea. I didn't use them this time as I could see the lip sync problems easily, and I wanted a good sound track in the video I was using for testing. I have local video sync test files for various frame rates, so I know how well my system keeps sync from local files. (Which isn't completely brilliant for all frames rates by the way, with a bit of drift, but over a long time and it corrects eventually.)
I should also try more Buffer and Latency combinations I guess. I have tried combinations of Recommended and Minimum, and a few others, but maybe I need to try a lot of others. I guess you have prompted me to do that at least, when I find time.
I should also set up the zones so I'm not tweaking my primary playback zone all the time. Then I will need an IPC zone. Oh, the complexity!
If we could just adjust the synchronisation of the video feed to the soundtrack, the WDM Driver would be fine. Functionality just like the Subtitles timing adjustment, that is saved to the file and has a default, would be great. But unless I have totally missed something in MC, we don't have that option.
PS: You were all the way up to 2005 posts by the time I saw this. You just can't help yourself, can you!