It never stops both in the gaming list or history panel, so you can imagine the sound chaos after selecting 3 games or more 
Can you check if the issue is solved in this layout, now the sound stops as soon as the fade out finishes. There might be some mixing of both sounds during fade out but it should work. Oh and the history page should work too...
Working perfectly now in game list and history panel, thanks again
There's a small bug that I just found related to this but I can live with it. Lets see if I can explain it:
Select a game (Bubble Bobble for example, can be any other), video starts playing, click button for context menu and chose history panel. There, scroll to left or right to other games, the video behavior with sound working perfect, etc. Now go back to the gaming list again. If you go the game you first selected to access the history panel and all the others you scrolled there before the last one you will notice that those videos start playing but now always without sound.
In other matter, I noticed that with Mame romlist if the list has the players numbers like "2P sim", "2P alt", "1P" and so on that will not appear in the players icon in the theme on top. Maybe this will help you if you want the code to check possible alternative entries in the lists.