Since the last couple of updates Youtube lipsync has been horrible, I mean really horrible. Some videos are fine, however I have a video you can test below that is reproducable.
For me it is really hard to get hold of this issue. I have experienced it on many different occasions in different apps. It seems to be a bit of a moving target also. It might depend on different factors like the source (probably frame rate) and the amount of video post processing (e.g. motion interpolation) that is being applied.
