Panasonic FZ82 videoing with
It seems that the main problem is not in the playback, but how the video was recorded. Check especially the frame rate options. High frame rate (like 120fps) video is sometimes played as slow motion video as default, and often the audio is not played at all (because it will sound unnatural). For normal video, select normal frame rates (25 or 30 fps is ok).
I hope this helps.