[johndoeee]

That's a framerate issue, e.g. 23.976 frame/s vs. 25 frame/s. Easily correctable, not sure if this service can handle that though.

[superasn]

Yes, it can automatically handle all frame-rate issues with time-shifting. What it can't handle is if there is an irregular break in between (say extra subtitles in between, extended versions, etc).

[jakubw]

Yes, that too, but that's not what I had in mind. I recall having to adjust the timing after a major block of footage, not permamently as would be the case with a mismatched framerate. Again, it might be a rare problem.