We can suggest a workaround. Vuo chooses one of two libraries — Apple AV Foundation or FFmpeg — to play a given movie, depending on the movie’s encoding and the Play Movie node’s Optimization setting. The bug only happens when using AV Foundation. So you can avoid it by convincing Vuo to use FFmpeg instead —
Set the Play Movie node’s Optimization input to Random.
If this fixes the problem, great, you’re done. Otherwise, check Vuo’s console (Tools > Show Console) for a message saying that AV Foundation was chosen to play the movie (“Using AvFoundation video decoder despite optimization preference”). This is just to make sure you’re on the right track for the workaround. (If instead it says that FFmpeg was used, let us know; that means there’s some other bug. )
Convert the movie to a format that Vuo’s FFmpeg player can read, such as HEVC video + AAC audio.
Run the composition again with the converted movie (and Optimization still set to Random). The movie should now play with FFmpeg and you should not encounter the audio bug.
The cause of the bug seems to be that, when you fast-forward the movie, AV Foundation’s audio and video streams get out of sync. When you resume normal speed, the audio from the segment you fast-forwarded through should have been discarded, but it gets queued up and played. We plan to fix the bug in an upcoming release.