I've come across a few videos that had the audio track set a
bit ahead and timecoded to give the file a bit of a cushion for
slower computers to keep the sound in sync. Unfortunately,
some player software is unable to detect the timing tweak
and plays the audio as it is found instead of as it is timecoded.

Media Player Classic has the option to adjust the timing, so
try playing the files with that. VLC has similar capabilities too.