If the voices don't seem to match the speakers on the video, it could be an issue with your software. Some people who use Windows Media Player have reported this issue.
We recommend using VLC player to watch the videos. The software is free and safe to use. Here is the link to download the software:
If this doesn't resolve the issue, please send us a message by live chat or email and we'd be happy to help you out! (firstname.lastname@example.org)