But if I use the PLAYS.TV tool to make a 1m30s edit of the whole recording the sound is back in sync again. The properties of the files are almost the same apart from the minimum frame rate.
I haven't tried editing, but I get the same issue when recording. The sound is slightly out of sync. I don't get the out of sync issue with FRAPS, I am pretty sure it isn't down to my computer specs.
Thanks for providing that info. I made a ticket for this issue that we'll continue to work on there. Ticket #5119