Windows 7 system to play web video silent how to do

Today, I encountered a strange thing. The local player listened to the song and watched the movie. But it played the flash of Tudou, Youku, Yo and other websites, as well as the RMVB and WMV videos in the online movie. There is no sound in the webpage. Can't listen. You can hear the sound by playing videos, music, and FLASH animations on your hard disk. It can be concluded that this has nothing to do with the driver. Reloading the drive did not help. If you have encountered such a problem, solve it together:
This problem is also very common in Windows XP/Vista. It is not related to Windows 7. Generally, what optimization software is used or various decoders are installed and uninstalled. Caused.
To solve this problem, click “Start"Menu→“Run" Enter “regedit” and press Enter to open the Registry Editor, click on the left pane and click "HKEY_LOCAL_MACHINE/" SOFTWARE/Microsoft/Windows NT/CurrentVersion/Drivers32”, then check in the right pane for the value of "wavemapper". If not, right-click in the blank space on the right pane to create a new string value called “wavemapper”, and then double-click the value to set its “Value Data” as “msacm32.drv”, Restart your computer to resolve the issue.
Tip: If there is no sound after setting according to the above method, please check if there is a volume icon in the system tray. If not, open “sound and audio device properties”, select “put the volume icon into the taskbar", and there will be a sound.